diff --git a/src/client/app/admin/views/federation.vue b/src/client/app/admin/views/federation.vue
index 6b09a3c28..25400393b 100644
--- a/src/client/app/admin/views/federation.vue
+++ b/src/client/app/admin/views/federation.vue
@@ -130,7 +130,7 @@
 					<span>{{ $t('status') }}</span>
 				</header>
 				<div v-for="instance in instances" :style="{ opacity: instance.isNotResponding ? 0.5 : 1 }">
-					<a @click.prevent="showInstance(instance.host)" target="_blank" :href="`https://${instance.host}`" :style="{ textDecoration: instance.isMarkedAsClosed ? 'line-through' : 'none' }">{{ instance.host }}</a>
+					<a @click.prevent="showInstance(instance.host)" rel="nofollow noopener" target="_blank" :href="`https://${instance.host}`" :style="{ textDecoration: instance.isMarkedAsClosed ? 'line-through' : 'none' }">{{ instance.host }}</a>
 					<span>{{ instance.notesCount | number }}</span>
 					<span>{{ instance.usersCount | number }}</span>
 					<span>{{ instance.followingCount | number }}</span>
diff --git a/src/client/app/common/views/components/forkit.vue b/src/client/app/common/views/components/forkit.vue
index 5629c5ac2..d652b846a 100644
--- a/src/client/app/common/views/components/forkit.vue
+++ b/src/client/app/common/views/components/forkit.vue
@@ -1,5 +1,5 @@
 <template>
-<a class="a" :href="repositoryUrl" target="_blank" title="View source on GitHub">
+<a class="a" :href="repositoryUrl" rel="noopener" target="_blank" title="View source on GitHub">
 	<svg width="80" height="80" viewBox="0 0 250 250" aria-hidden="aria-hidden">
 		<path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
 		<path class="octo-arm" d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2" fill="currentColor"></path>
diff --git a/src/client/app/common/views/components/integrations.integration.vue b/src/client/app/common/views/components/integrations.integration.vue
index 8be9d9955..51995843b 100644
--- a/src/client/app/common/views/components/integrations.integration.vue
+++ b/src/client/app/common/views/components/integrations.integration.vue
@@ -1,5 +1,5 @@
 <template>
-<a class="zxrjzpcj" :href="url" :class="service" target="_blank">
+<a class="zxrjzpcj" :href="url" :class="service" rel="noopener" target="_blank">
 	<fa :icon="icon" size="lg" fixed-width /><span>{{ text }}</span>
 </a>
 </template>
diff --git a/src/client/app/common/views/components/messaging-room.message.vue b/src/client/app/common/views/components/messaging-room.message.vue
index 256ea760b..908533e0c 100644
--- a/src/client/app/common/views/components/messaging-room.message.vue
+++ b/src/client/app/common/views/components/messaging-room.message.vue
@@ -9,7 +9,7 @@
 			<div class="content" v-if="!message.isDeleted">
 				<mfm class="text" v-if="message.text" ref="text" :text="message.text" :i="$store.state.i"/>
 				<div class="file" v-if="message.file">
-					<a :href="message.file.url" target="_blank" :title="message.file.name">
+					<a :href="message.file.url" rel="noopener" target="_blank" :title="message.file.name">
 						<img v-if="message.file.type.split('/')[0] == 'image'" :src="message.file.url" :alt="message.file.name"
 							:style="{ backgroundColor: message.file.properties.avgColor || 'transparent' }"/>
 						<p v-else>{{ message.file.name }}</p>
diff --git a/src/client/app/common/views/components/mfm.ts b/src/client/app/common/views/components/mfm.ts
index 78734200a..945917288 100644
--- a/src/client/app/common/views/components/mfm.ts
+++ b/src/client/app/common/views/components/mfm.ts
@@ -174,6 +174,7 @@ export default Vue.component('misskey-flavored-markdown', {
 						key: Math.random(),
 						props: {
 							url: token.node.props.url,
+							rel: 'nofollow noopener',
 							target: '_blank'
 						},
 						attrs: {
@@ -187,6 +188,7 @@ export default Vue.component('misskey-flavored-markdown', {
 						attrs: {
 							class: 'link',
 							href: token.node.props.url,
+							rel: 'nofollow noopener',
 							target: '_blank',
 							title: token.node.props.url,
 							style: 'color:var(--mfmLink);'
diff --git a/src/client/app/common/views/components/nav.vue b/src/client/app/common/views/components/nav.vue
index a8f9bb928..9d4e7091b 100644
--- a/src/client/app/common/views/components/nav.vue
+++ b/src/client/app/common/views/components/nav.vue
@@ -2,9 +2,9 @@
 <span class="mk-nav">
 	<a :href="aboutUrl">{{ $t('about') }}</a>
 	<i>・</i>
-	<a :href="repositoryUrl">{{ $t('repository') }}</a>
+	<a :href="repositoryUrl" rel="noopener" target="_blank">{{ $t('repository') }}</a>
 	<i>・</i>
-	<a :href="feedbackUrl" target="_blank">{{ $t('feedback') }}</a>
+	<a :href="feedbackUrl" rel="noopener" target="_blank">{{ $t('feedback') }}</a>
 	<i>・</i>
 	<a href="/dev">{{ $t('develop') }}</a>
 </span>
diff --git a/src/client/app/common/views/components/settings/2fa.vue b/src/client/app/common/views/components/settings/2fa.vue
index 07a149315..6e8d19d83 100644
--- a/src/client/app/common/views/components/settings/2fa.vue
+++ b/src/client/app/common/views/components/settings/2fa.vue
@@ -9,7 +9,7 @@
 	</template>
 	<div v-if="data && !$store.state.i.twoFactorEnabled">
 		<ol>
-			<li>{{ $t('authenticator') }}<a href="https://support.google.com/accounts/answer/1066447" target="_blank">{{ $t('howtoinstall') }}</a></li>
+			<li>{{ $t('authenticator') }}<a href="https://support.google.com/accounts/answer/1066447" rel="noopener" target="_blank">{{ $t('howtoinstall') }}</a></li>
 			<li>{{ $t('scan') }}<br><img :src="data.qr"></li>
 			<li>{{ $t('done') }}<br>
 				<ui-input v-model="token">{{ $t('token') }}</ui-input>
diff --git a/src/client/app/common/views/components/settings/integration.vue b/src/client/app/common/views/components/settings/integration.vue
index 8ac0c134c..71ad8b450 100644
--- a/src/client/app/common/views/components/settings/integration.vue
+++ b/src/client/app/common/views/components/settings/integration.vue
@@ -4,21 +4,21 @@
 
 	<section v-if="enableTwitterIntegration">
 		<header><fa :icon="['fab', 'twitter']"/> Twitter</header>
-		<p v-if="$store.state.i.twitter">{{ $t('connected-to') }}: <a :href="`https://twitter.com/${$store.state.i.twitter.screenName}`" target="_blank">@{{ $store.state.i.twitter.screenName }}</a></p>
+		<p v-if="$store.state.i.twitter">{{ $t('connected-to') }}: <a :href="`https://twitter.com/${$store.state.i.twitter.screenName}`" rel="nofollow noopener" target="_blank">@{{ $store.state.i.twitter.screenName }}</a></p>
 		<ui-button v-if="$store.state.i.twitter" @click="disconnectTwitter">{{ $t('disconnect') }}</ui-button>
 		<ui-button v-else @click="connectTwitter">{{ $t('connect') }}</ui-button>
 	</section>
 
 	<section v-if="enableDiscordIntegration">
 		<header><fa :icon="['fab', 'discord']"/> Discord</header>
-		<p v-if="$store.state.i.discord">{{ $t('connected-to') }}: <a :href="`https://discordapp.com/users/${$store.state.i.discord.id}`" target="_blank">@{{ $store.state.i.discord.username }}#{{ $store.state.i.discord.discriminator }}</a></p>
+		<p v-if="$store.state.i.discord">{{ $t('connected-to') }}: <a :href="`https://discordapp.com/users/${$store.state.i.discord.id}`" rel="nofollow noopener" target="_blank">@{{ $store.state.i.discord.username }}#{{ $store.state.i.discord.discriminator }}</a></p>
 		<ui-button v-if="$store.state.i.discord" @click="disconnectDiscord">{{ $t('disconnect') }}</ui-button>
 		<ui-button v-else @click="connectDiscord">{{ $t('connect') }}</ui-button>
 	</section>
 
 	<section v-if="enableGithubIntegration">
 		<header><fa :icon="['fab', 'github']"/> GitHub</header>
-		<p v-if="$store.state.i.github">{{ $t('connected-to') }}: <a :href="`https://github.com/${$store.state.i.github.login}`" target="_blank">@{{ $store.state.i.github.login }}</a></p>
+		<p v-if="$store.state.i.github">{{ $t('connected-to') }}: <a :href="`https://github.com/${$store.state.i.github.login}`" rel="nofollow noopener" target="_blank">@{{ $store.state.i.github.login }}</a></p>
 		<ui-button v-if="$store.state.i.github" @click="disconnectGithub">{{ $t('disconnect') }}</ui-button>
 		<ui-button v-else @click="connectGithub">{{ $t('connect') }}</ui-button>
 	</section>
diff --git a/src/client/app/common/views/components/settings/theme.vue b/src/client/app/common/views/components/settings/theme.vue
index b1f7b2bc4..3e6b9133c 100644
--- a/src/client/app/common/views/components/settings/theme.vue
+++ b/src/client/app/common/views/components/settings/theme.vue
@@ -45,7 +45,7 @@
 			</ui-select>
 		</label>
 
-		<a href="https://assets.msky.cafe/theme/list" target="_blank">{{ $t('find-more-theme') }}</a>
+		<a href="https://assets.msky.cafe/theme/list" rel="noopener" target="_blank">{{ $t('find-more-theme') }}</a>
 
 		<details class="creator">
 			<summary><fa icon="palette"/> {{ $t('create-a-theme') }}</summary>
diff --git a/src/client/app/common/views/components/url-preview.vue b/src/client/app/common/views/components/url-preview.vue
index af5f3e4eb..9ca4497ad 100644
--- a/src/client/app/common/views/components/url-preview.vue
+++ b/src/client/app/common/views/components/url-preview.vue
@@ -9,7 +9,7 @@
 	</blockquote>
 </div>
 <div v-else class="mk-url-preview">
-	<a :class="{ mini: narrow, compact }" :href="url" target="_blank" :title="url" v-if="!fetching">
+	<a :class="{ mini: narrow, compact }" :href="url" rel="nofollow noopener" target="_blank" :title="url" v-if="!fetching">
 		<div class="thumbnail" v-if="thumbnail" :style="`background-image: url('${thumbnail}')`">
 			<button v-if="!playerEnabled && player.url" @click.prevent="playerEnabled = true" :title="$t('enable-player')"><fa :icon="['far', 'play-circle']"/></button>
 		</div>
diff --git a/src/client/app/common/views/components/url.vue b/src/client/app/common/views/components/url.vue
index 2daf79cba..faf439814 100644
--- a/src/client/app/common/views/components/url.vue
+++ b/src/client/app/common/views/components/url.vue
@@ -1,5 +1,5 @@
 <template>
-<a class="mk-url" :href="url" :target="target">
+<a class="mk-url" :href="url" :rel="rel" :target="target">
 	<span class="schema">{{ schema }}//</span>
 	<span class="hostname">{{ hostname }}</span>
 	<span class="port" v-if="port != ''">:{{ port }}</span>
@@ -15,7 +15,7 @@ import Vue from 'vue';
 import { toUnicode as decodePunycode } from 'punycode';
 
 export default Vue.extend({
-	props: ['url', 'target'],
+	props: ['url', 'rel', 'target'],
 	data() {
 		return {
 			schema: null,
diff --git a/src/client/app/common/views/deck/deck.note-column.vue b/src/client/app/common/views/deck/deck.note-column.vue
index ddc3860d3..bcc887e2f 100644
--- a/src/client/app/common/views/deck/deck.note-column.vue
+++ b/src/client/app/common/views/deck/deck.note-column.vue
@@ -8,7 +8,7 @@
 		<div class="is-remote" v-if="note.user.host != null">
 			<details>
 				<summary><fa icon="exclamation-triangle"/> {{ $t('@.is-remote-post') }}</summary>
-				<a :href="note.url || note.uri" target="_blank">{{ $t('@.view-on-remote') }}</a>
+				<a :href="note.url || note.uri" rel="nofollow noopener" target="_blank">{{ $t('@.view-on-remote') }}</a>
 			</details>
 		</div>
 		<mk-note :note="note" :detail="true" :key="note.id"/>
diff --git a/src/client/app/common/views/deck/deck.user-column.vue b/src/client/app/common/views/deck/deck.user-column.vue
index 8d1b458a8..c508f3f69 100644
--- a/src/client/app/common/views/deck/deck.user-column.vue
+++ b/src/client/app/common/views/deck/deck.user-column.vue
@@ -8,7 +8,7 @@
 		<div class="is-remote" v-if="user.host != null">
 			<details>
 				<summary><fa icon="exclamation-triangle"/> {{ $t('@.is-remote-user') }}</summary>
-				<a :href="user.url" target="_blank">{{ $t('@.view-on-remote') }}</a>
+				<a :href="user.url" rel="nofollow noopener" target="_blank">{{ $t('@.view-on-remote') }}</a>
 			</details>
 		</div>
 		<header :style="bannerStyle">
diff --git a/src/client/app/common/views/widgets/rss.vue b/src/client/app/common/views/widgets/rss.vue
index e97919767..c1a66bfeb 100644
--- a/src/client/app/common/views/widgets/rss.vue
+++ b/src/client/app/common/views/widgets/rss.vue
@@ -7,7 +7,7 @@
 		<div class="mkw-rss--body" :data-mobile="platform == 'mobile'">
 			<p class="fetching" v-if="fetching"><fa icon="spinner" pulse fixed-width/>{{ $t('@.loading') }}<mk-ellipsis/></p>
 			<div class="feed" v-else>
-				<a v-for="item in items" :href="item.link" target="_blank" :title="item.title">{{ item.title }}</a>
+				<a v-for="item in items" :href="item.link" rel="nofollow noopener" target="_blank" :title="item.title">{{ item.title }}</a>
 			</div>
 		</div>
 	</ui-container>
diff --git a/src/client/app/desktop/views/components/note-detail.vue b/src/client/app/desktop/views/components/note-detail.vue
index bcff8c877..e0ce5ce1c 100644
--- a/src/client/app/desktop/views/components/note-detail.vue
+++ b/src/client/app/desktop/views/components/note-detail.vue
@@ -54,7 +54,7 @@
 				</div>
 				<mk-poll v-if="appearNote.poll" :note="appearNote"/>
 				<mk-url-preview v-for="url in urls" :url="url" :key="url" :detail="true"/>
-				<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" target="_blank"><fa icon="map-marker-alt"/> {{ $t('location') }}</a>
+				<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" rel="noopener" target="_blank"><fa icon="map-marker-alt"/> {{ $t('location') }}</a>
 				<div class="map" v-if="appearNote.geo" ref="map"></div>
 				<div class="renote" v-if="appearNote.renote">
 					<mk-note-preview :note="appearNote.renote"/>
diff --git a/src/client/app/desktop/views/components/note.vue b/src/client/app/desktop/views/components/note.vue
index 585294fc8..1c00faed3 100644
--- a/src/client/app/desktop/views/components/note.vue
+++ b/src/client/app/desktop/views/components/note.vue
@@ -32,7 +32,7 @@
 						<mk-media-list :media-list="appearNote.files"/>
 					</div>
 					<mk-poll v-if="appearNote.poll" :note="appearNote" ref="pollViewer"/>
-					<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" target="_blank"><fa icon="map-marker-alt"/> 位置情報</a>
+					<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" rel="noopener" target="_blank"><fa icon="map-marker-alt"/> 位置情報</a>
 					<div class="renote" v-if="appearNote.renote"><mk-note-preview :note="appearNote.renote"/></div>
 					<mk-url-preview v-for="url in urls" :url="url" :key="url" :compact="compact"/>
 				</div>
diff --git a/src/client/app/desktop/views/home/user/index.vue b/src/client/app/desktop/views/home/user/index.vue
index 338cd1c59..98ad165d9 100644
--- a/src/client/app/desktop/views/home/user/index.vue
+++ b/src/client/app/desktop/views/home/user/index.vue
@@ -4,7 +4,7 @@
 		<fa icon="exclamation-triangle"/> {{ $t('@.user-suspended') }}
 	</div>
 	<div class="is-remote" v-if="user.host != null" :class="{ shadow: $store.state.device.useShadow, round: $store.state.device.roundedCorners }">
-		<fa icon="exclamation-triangle"/> {{ $t('@.is-remote-user') }}<a :href="user.url" target="_blank">{{ $t('@.view-on-remote') }}</a>
+		<fa icon="exclamation-triangle"/> {{ $t('@.is-remote-user') }}<a :href="user.url" rel="nofollow noopener" target="_blank">{{ $t('@.view-on-remote') }}</a>
 	</div>
 	<div class="main">
 		<x-header class="header" :user="user"/>
diff --git a/src/client/app/mobile/views/components/media-video.vue b/src/client/app/mobile/views/components/media-video.vue
index 1bf282b4a..044bb4c10 100644
--- a/src/client/app/mobile/views/components/media-video.vue
+++ b/src/client/app/mobile/views/components/media-video.vue
@@ -7,6 +7,7 @@
 </div>
 <a class="kkjnbbplepmiyuadieoenjgutgcmtsvu" v-else
 	:href="video.url"
+	rel="nofollow noopener"
 	target="_blank"
 	:style="imageStyle"
 	:title="video.name"
diff --git a/src/client/app/mobile/views/components/note-detail.vue b/src/client/app/mobile/views/components/note-detail.vue
index 4b343491b..358b827a5 100644
--- a/src/client/app/mobile/views/components/note-detail.vue
+++ b/src/client/app/mobile/views/components/note-detail.vue
@@ -40,7 +40,7 @@
 				</div>
 				<mk-poll v-if="appearNote.poll" :note="appearNote"/>
 				<mk-url-preview v-for="url in urls" :url="url" :key="url" :detail="true"/>
-				<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" target="_blank"><fa icon="map-marker-alt"/> {{ $t('location') }}</a>
+				<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" rel="noopener" target="_blank"><fa icon="map-marker-alt"/> {{ $t('location') }}</a>
 				<div class="map" v-if="appearNote.geo" ref="map"></div>
 				<div class="renote" v-if="appearNote.renote">
 					<mk-note-preview :note="appearNote.renote"/>
diff --git a/src/client/app/mobile/views/components/note.vue b/src/client/app/mobile/views/components/note.vue
index c207eb10d..01514f05f 100644
--- a/src/client/app/mobile/views/components/note.vue
+++ b/src/client/app/mobile/views/components/note.vue
@@ -32,7 +32,7 @@
 					</div>
 					<mk-poll v-if="appearNote.poll" :note="appearNote" ref="pollViewer"/>
 					<mk-url-preview v-for="url in urls" :url="url" :key="url" :compact="true"/>
-					<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" target="_blank"><fa icon="map-marker-alt"/> {{ $t('location') }}</a>
+					<a class="location" v-if="appearNote.geo" :href="`https://maps.google.com/maps?q=${appearNote.geo.coordinates[1]},${appearNote.geo.coordinates[0]}`" rel="noopener" target="_blank"><fa icon="map-marker-alt"/> {{ $t('location') }}</a>
 					<div class="renote" v-if="appearNote.renote"><mk-note-preview :note="appearNote.renote"/></div>
 				</div>
 				<span class="app" v-if="appearNote.app && $store.state.settings.showVia">via <b>{{ appearNote.app.name }}</b></span>
diff --git a/src/client/app/mobile/views/pages/user/index.vue b/src/client/app/mobile/views/pages/user/index.vue
index 7afa06d4a..f8f4719a6 100644
--- a/src/client/app/mobile/views/pages/user/index.vue
+++ b/src/client/app/mobile/views/pages/user/index.vue
@@ -5,7 +5,7 @@
 	</template>
 	<div class="wwtwuxyh" v-if="!fetching">
 		<div class="is-suspended" v-if="user.isSuspended"><p><fa icon="exclamation-triangle"/> {{ $t('@.user-suspended') }}</p></div>
-		<div class="is-remote" v-if="user.host != null"><p><fa icon="exclamation-triangle"/> {{ $t('@.is-remote-user') }}<a :href="user.url" target="_blank">{{ $t('@.view-on-remote') }}</a></p></div>
+		<div class="is-remote" v-if="user.host != null"><p><fa icon="exclamation-triangle"/> {{ $t('@.is-remote-user') }}<a :href="user.url" rel="nofollow noopener" target="_blank">{{ $t('@.view-on-remote') }}</a></p></div>
 		<header>
 			<div class="banner" :style="style"></div>
 			<div class="body">
diff --git a/src/docs/article.pug b/src/docs/article.pug
index 38494fec6..48f501d40 100644
--- a/src/docs/article.pug
+++ b/src/docs/article.pug
@@ -6,4 +6,4 @@ block main
 block footer
 	p
 		= i18n('docs.edit-this-page-on-github')
-		a(href=src target="_blank")= i18n('docs.edit-this-page-on-github-link')
+		a(href=src rel="noopener" target="_blank")= i18n('docs.edit-this-page-on-github-link')
diff --git a/src/server/web/views/note.pug b/src/server/web/views/note.pug
index 983c731a0..0580e959f 100644
--- a/src/server/web/views/note.pug
+++ b/src/server/web/views/note.pug
@@ -26,6 +26,9 @@ block meta
 	meta(name='twitter:card' content='summary')
 
 	// todo
+	if user.host
+		meta(name='robots' content='noindex')
+
 	if user.twitter
 		meta(name='twitter:creator' content=`@${user.twitter.screenName}`)
 
diff --git a/src/server/web/views/user.pug b/src/server/web/views/user.pug
index bff98ba80..9b257afb7 100644
--- a/src/server/web/views/user.pug
+++ b/src/server/web/views/user.pug
@@ -24,6 +24,9 @@ block meta
 
 	meta(name='twitter:card' content='summary')
 
+	if user.host
+		meta(name='robots' content='noindex')
+
 	if profile.twitter
 		meta(name='twitter:creator' content=`@${profile.twitter.screenName}`)