diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6735f7106..87449f0be 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,7 @@
 -
 
 ### Server
--
+- Fix: DBマイグレーション際にシステムアカウントのユーザーID判定が正しくない問題を修正
 
 
 ## 2025.3.0
diff --git a/packages/backend/migration/1741279404074-system-accounts-fixup.js b/packages/backend/migration/1741279404074-system-accounts-fixup.js
new file mode 100644
index 000000000..31cab7f5a
--- /dev/null
+++ b/packages/backend/migration/1741279404074-system-accounts-fixup.js
@@ -0,0 +1,26 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export class SystemAccounts1741279404074 {
+    name = 'SystemAccounts1741279404074'
+
+    async up(queryRunner) {
+        const instanceActor = await queryRunner.query(`SELECT "id" FROM "user" WHERE "username" = 'instance.actor' AND "host" IS NULL AND "id" NOT IN (SELECT "userId" FROM "system_account" WHERE "type" = 'actor')`);
+        if (instanceActor.length > 0) {
+            console.warn('instance.actor was incorrect, updating...');
+            await queryRunner.query(`UPDATE "system_account" SET "id" = '${instanceActor[0].id}', "userId" = '${instanceActor[0].id}' WHERE "type" = 'actor'`);
+        }
+
+        const relayActor = await queryRunner.query(`SELECT "id" FROM "user" WHERE "username" = 'relay.actor' AND "host" IS NULL AND "id" NOT IN (SELECT "userId" FROM "system_account" WHERE "type" = 'relay')`);
+        if (relayActor.length > 0) {
+            console.warn('relay.actor was incorrect, updating...');
+            await queryRunner.query(`UPDATE "system_account" SET "id" = '${relayActor[0].id}', "userId" = '${relayActor[0].id}' WHERE "type" = 'relay'`);
+        }
+    }
+
+    async down(queryRunner) {
+        // fixup migration, no down migration
+    }
+}