diff --git a/packages/backend/src/remote/activitypub/kernel/index.ts b/packages/backend/src/remote/activitypub/kernel/index.ts
index b8af3dc48..e24af2b38 100644
--- a/packages/backend/src/remote/activitypub/kernel/index.ts
+++ b/packages/backend/src/remote/activitypub/kernel/index.ts
@@ -18,6 +18,7 @@ import {
 	isCollection,
 	isFlag,
 	isMove,
+	getApId,
 } from '../type.js';
 import { apLogger } from '../logger.js';
 import Resolver from '../resolver.js';
@@ -37,6 +38,8 @@ import block from './block/index.js';
 import flag from './flag/index.js';
 import move from './move/index.js';
 import type { IObject } from '../type.js';
+import { extractDbHost } from '@/misc/convert-host.js';
+import { shouldBlockInstance } from '@/misc/should-block-instance.js';
 
 export async function performActivity(actor: CacheableRemoteUser, activity: IObject) {
 	if (isCollectionOrOrderedCollection(activity)) {
@@ -59,6 +62,12 @@ export async function performActivity(actor: CacheableRemoteUser, activity: IObj
 async function performOneActivity(actor: CacheableRemoteUser, activity: IObject): Promise<void> {
 	if (actor.isSuspended) return;
 
+	if (typeof activity.id !== 'undefined') {
+		const host = extractDbHost(getApId(activity));
+		if (await shouldBlockInstance(host)) return;
+	}
+
+
 	if (isCreate(activity)) {
 		await create(actor, activity);
 	} else if (isDelete(activity)) {
diff --git a/packages/backend/src/remote/activitypub/resolver.ts b/packages/backend/src/remote/activitypub/resolver.ts
index 8958c892a..e4fdedac9 100644
--- a/packages/backend/src/remote/activitypub/resolver.ts
+++ b/packages/backend/src/remote/activitypub/resolver.ts
@@ -5,7 +5,7 @@ import { getInstanceActor } from '@/services/instance-actor.js';
 import { fetchMeta } from '@/misc/fetch-meta.js';
 import { extractDbHost, isSelfHost } from '@/misc/convert-host.js';
 import { signedGet } from './request.js';
-import { IObject, isCollectionOrOrderedCollection, ICollection, IOrderedCollection } from './type.js';
+import { IObject, isCollectionOrOrderedCollection, ICollection, IOrderedCollection, getApId } from './type.js';
 import { FollowRequests, Notes, NoteReactions, Polls, Users } from '@/models/index.js';
 import { parseUri } from './db-resolver.js';
 import renderNote from '@/remote/activitypub/renderer/note.js';
@@ -49,6 +49,12 @@ export default class Resolver {
 		}
 
 		if (typeof value !== 'string') {
+			if (typeof value.id !== 'undefined') {
+				const host = extractDbHost(getApId(value));
+				if (await shouldBlockInstance(host)) {
+					throw new Error('instance is blocked');
+				}
+			}
 			return value;
 		}