diff --git a/src/common/othello/core.ts b/src/common/othello/core.ts
index e7e725aaf..3a181a3eb 100644
--- a/src/common/othello/core.ts
+++ b/src/common/othello/core.ts
@@ -224,10 +224,15 @@ export default class Othello {
 
 				// 座標が指し示す位置がボード外に出たとき
 				if (this.opts.loopedBoard) {
-					if (x <  0             ) x = this.mapWidth - (-x);
-					if (y <  0             ) y = this.mapHeight - (-y);
-					if (x >= this.mapWidth ) x = x - this.mapWidth;
-					if (y >= this.mapHeight) y = y - this.mapHeight;
+					if (x <  0             ) x = this.mapWidth - ((-x) % this.mapWidth);
+					if (y <  0             ) y = this.mapHeight - ((-y) % this.mapHeight);
+					if (x >= this.mapWidth ) x = x % this.mapWidth;
+					if (y >= this.mapHeight) y = y % this.mapHeight;
+
+					// for debug
+					//if (x < 0 || y < 0 || x >= this.mapWidth || y >= this.mapHeight) {
+					//	console.log(x, y);
+					//}
 
 					// 一周して自分に帰ってきたら
 					if (this.transformXyToPos(x, y) == initPos) break;
diff --git a/src/common/othello/maps.ts b/src/common/othello/maps.ts
index 3518259bb..81b9663c3 100644
--- a/src/common/othello/maps.ts
+++ b/src/common/othello/maps.ts
@@ -815,3 +815,22 @@ export const test2: Map = {
 		'-w--b-'
 	]
 };
+
+export const test3: Map = {
+	name: 'Test3',
+	category: 'Test',
+	data: [
+		'-w-',
+		'--w',
+		'w--',
+		'-w-',
+		'--w',
+		'w--',
+		'-w-',
+		'--w',
+		'w--',
+		'-w-',
+		'---',
+		'b--',
+	]
+};