diff --git a/packages/backend/migration/1745378064470-composite-note-index.js b/packages/backend/migration/1745378064470-composite-note-index.js
index 49e835d38c..773afb636c 100644
--- a/packages/backend/migration/1745378064470-composite-note-index.js
+++ b/packages/backend/migration/1745378064470-composite-note-index.js
@@ -5,9 +5,10 @@
 
 export class CompositeNoteIndex1745378064470 {
 	name = 'CompositeNoteIndex1745378064470';
+	transaction = false;
 
 	async up(queryRunner) {
-		await queryRunner.query(`CREATE INDEX "IDX_724b311e6f883751f261ebe378" ON "note" ("userId", "id" DESC)`);
+		await queryRunner.query(`CREATE INDEX CONCURRENTLY "IDX_724b311e6f883751f261ebe378" ON "note" ("userId", "id" DESC)`);
 		await queryRunner.query(`DROP INDEX IF EXISTS "IDX_5b87d9d19127bd5d92026017a7"`);
 		// Flush all cached Linear Scan Plans and redo statistics for composite index
 		// this is important for Postgres to learn that even in highly complex queries, using this index first can reduce the result set significantly
@@ -16,6 +17,6 @@ export class CompositeNoteIndex1745378064470 {
 
 	async down(queryRunner) {
 		await queryRunner.query(`DROP INDEX IF EXISTS "IDX_724b311e6f883751f261ebe378"`);
-		await queryRunner.query(`CREATE INDEX "IDX_5b87d9d19127bd5d92026017a7" ON "note" ("userId")`);
+		await queryRunner.query(`CREATE INDEX CONCURRENTLY "IDX_5b87d9d19127bd5d92026017a7" ON "note" ("userId")`);
 	}
 }
diff --git a/packages/backend/ormconfig.js b/packages/backend/ormconfig.js
index 229e5bf1fe..23774f21fd 100644
--- a/packages/backend/ormconfig.js
+++ b/packages/backend/ormconfig.js
@@ -14,4 +14,5 @@ export default new DataSource({
 	extra: config.db.extra,
 	entities: entities,
 	migrations: ['migration/*.js'],
+	migrationsTransactionMode: 'each',
 });
diff --git a/packages/backend/src/models/Note.ts b/packages/backend/src/models/Note.ts
index c5ca2b5776..fe499bdc0b 100644
--- a/packages/backend/src/models/Note.ts
+++ b/packages/backend/src/models/Note.ts
@@ -10,7 +10,13 @@ import { MiUser } from './User.js';
 import { MiChannel } from './Channel.js';
 import type { MiDriveFile } from './DriveFile.js';
 
-@Index(['userId', 'id'])
+// Note: When you create a new index for existing column of this table,
+// it might be better to index concurrently by setting `{ concurrent: true }`.
+// Since this table is very large, and it takes a long time to create index in most cases.
+// Please note that `CREATE INDEX CONCURRENTLY` is not supported in transaction,
+// so you need to set `transaction = false` in migration.
+// Please refer 1745378064470-composite-note-index.js for example.
+@Index(['userId', 'id'], { concurrent: true })
 @Entity('note')
 export class MiNote {
 	@PrimaryColumn(id())