diff --git a/migration/1621479946000-add-note-indexes.ts b/migration/1621479946000-add-note-indexes.ts
new file mode 100644
index 0000000000000000000000000000000000000000..53d49964a7eafd3c66a9d30261274fcd9783c743
--- /dev/null
+++ b/migration/1621479946000-add-note-indexes.ts
@@ -0,0 +1,16 @@
+import {MigrationInterface, QueryRunner} from "typeorm";
+
+export class addNoteIndexes1621479946000 implements MigrationInterface {
+    name = 'addNoteIndexes1621479946000'
+
+    public async up(queryRunner: QueryRunner): Promise<void> {
+        await queryRunner.query(`CREATE INDEX "IDX_NOTE_MENTIONS" ON "note" USING gin ("mentions")`, undefined);
+				await queryRunner.query(`CREATE INDEX "IDX_NOTE_VISIBLE_USER_IDS" ON "note" USING gin ("visibleUserIds")`, undefined);
+    }
+
+    public async down(queryRunner: QueryRunner): Promise<void> {
+        await queryRunner.query(`DROP INDEX "IDX_NOTE_MENTIONS"`, undefined);
+				await queryRunner.query(`DROP INDEX "IDX_NOTE_VISIBLE_USER_IDS"`, undefined);
+    }
+
+}
diff --git a/src/models/entities/note.ts b/src/models/entities/note.ts
index 2be7d2b33c12624cece2e9c9ca097f2682a700f9..9a85532637bde8788834424190945ac8c16467fe 100644
--- a/src/models/entities/note.ts
+++ b/src/models/entities/note.ts
@@ -7,6 +7,8 @@ import { Channel } from './channel';
 
 @Entity()
 @Index('IDX_NOTE_TAGS', { synchronize: false })
+@Index('IDX_NOTE_MENTIONS', { synchronize: false })
+@Index('IDX_NOTE_VISIBLE_USER_IDS', { synchronize: false })
 export class Note {
 	@PrimaryColumn(id())
 	public id: string;
diff --git a/src/server/api/common/generate-visibility-query.ts b/src/server/api/common/generate-visibility-query.ts
index 72ed1c46eaeacbc99f6c3603bc015f1d24b1eb0e..00a50f821167732a1c4fcadad37e4b374a6270a6 100644
--- a/src/server/api/common/generate-visibility-query.ts
+++ b/src/server/api/common/generate-visibility-query.ts
@@ -22,7 +22,7 @@ export function generateVisibilityQuery(q: SelectQueryBuilder<any>, me?: { id: U
 			// または 自分自身
 			.orWhere('note.userId = :userId1', { userId1: me.id })
 			// または 自分宛て
-			.orWhere(':userId2 = ANY(note.visibleUserIds)', { userId2: me.id })
+			.orWhere(`'{"${me.id}"}' <@ note.visibleUserIds`)
 			.orWhere(new Brackets(qb => { qb
 				// または フォロワー宛ての投稿であり、
 				.where('note.visibility = \'followers\'')
diff --git a/src/server/api/endpoints/notes/mentions.ts b/src/server/api/endpoints/notes/mentions.ts
index 34936c9b54ffd9444c4db605cfd5eebf477c7174..dddd08eee6caa8e1f10895700f11b0dd7618527d 100644
--- a/src/server/api/endpoints/notes/mentions.ts
+++ b/src/server/api/endpoints/notes/mentions.ts
@@ -60,8 +60,8 @@ export default define(meta, async (ps, user) => {
 
 	const query = makePaginationQuery(Notes.createQueryBuilder('note'), ps.sinceId, ps.untilId)
 		.andWhere(new Brackets(qb => { qb
-			.where(`:meId = ANY(note.mentions)`, { meId: user.id })
-			.orWhere(`:meId = ANY(note.visibleUserIds)`, { meId: user.id });
+			.where(`'{"${user.id}"}' <@ note.mentions`)
+			.orWhere(`'{"${user.id}"}' <@ note.visibleUserIds`);
 		}))
 		.innerJoinAndSelect('note.user', 'user')
 		.leftJoinAndSelect('note.reply', 'reply')