diff --git a/packages/backend/src/core/ChatService.ts b/packages/backend/src/core/ChatService.ts
index 5cd336a097..565141ea9c 100644
--- a/packages/backend/src/core/ChatService.ts
+++ b/packages/backend/src/core/ChatService.ts
@@ -28,6 +28,8 @@ import { CustomEmojiService } from '@/core/CustomEmojiService.js';
 import { emojiRegex } from '@/misc/emoji-regex.js';
 import { NotificationService } from '@/core/NotificationService.js';
 import { ModerationLogService } from '@/core/ModerationLogService.js';
+import { ApDeliverManagerService } from '@/core/activitypub/ApDeliverManagerService.js';
+import { trackPromise } from '@/misc/promise-tracker.js';
 
 const MAX_ROOM_MEMBERS = 50;
 const MAX_REACTIONS_PER_MESSAGE = 100;
@@ -81,6 +83,7 @@ export class ChatService {
 		private chatEntityService: ChatEntityService,
 		private idService: IdService,
 		private globalEventService: GlobalEventService,
+		private apDeliverManagerService: ApDeliverManagerService,
 		private apRendererService: ApRendererService,
 		private queueService: QueueService,
 		private pushNotificationService: PushNotificationService,
@@ -236,6 +239,19 @@ export class ChatService {
 			}, 3000);
 		}
 
+		//#region AP deliver
+		if (this.userEntityService.isLocalUser(fromUser) && this.userEntityService.isRemoteUser(toUser)) {
+			(async () => {
+				const content = await this.apRendererService.renderChatMessage(inserted, false);
+				const activity = this.apRendererService.addContext(content);
+
+				const dm = this.apDeliverManagerService.createDeliverManager(fromUser, activity);
+				dm.addDirectRecipe(toUser);
+				trackPromise(dm.execute());
+			})();
+		}
+		//#endregion
+
 		return packedMessage;
 	}
 
diff --git a/packages/backend/src/core/activitypub/ApInboxService.ts b/packages/backend/src/core/activitypub/ApInboxService.ts
index e88f60b806..786f2078d5 100644
--- a/packages/backend/src/core/activitypub/ApInboxService.ts
+++ b/packages/backend/src/core/activitypub/ApInboxService.ts
@@ -457,6 +457,36 @@ export class ApInboxService {
 		}
 	}
 
+	@bindThis
+	private async chatMessage(resolver: Resolver, actor: MiRemoteUser, message: IObject): Promise<string> {
+		const uri = getApId(message);
+
+		if (typeof message === 'object') {
+			if (actor.uri !== message.attributedTo) {
+				return 'skip: actor.uri !== message.attributedTo';
+			}
+
+			if (typeof message.id === 'string') {
+				if (this.utilityService.extractDbHost(actor.uri) !== this.utilityService.extractDbHost(message.id)) {
+					return 'skip: host in actor.uri !== message.id';
+				}
+			} else {
+				return 'skip: message.id is not a string';
+			}
+		}
+
+		try {
+			await this.chatService.createMessageViaAp(message, actor, resolver);
+			return 'ok';
+		} catch (err) {
+			if (err instanceof StatusError && !err.isRetryable) {
+				return `skip ${err.statusCode}`;
+			} else {
+				throw err;
+			}
+		}
+	}
+
 	@bindThis
 	private async delete(actor: MiRemoteUser, activity: IDelete): Promise<string> {
 		if (actor.uri !== activity.actor) {
diff --git a/packages/backend/src/core/activitypub/ApRendererService.ts b/packages/backend/src/core/activitypub/ApRendererService.ts
index 55521d6e3a..0bf6627491 100644
--- a/packages/backend/src/core/activitypub/ApRendererService.ts
+++ b/packages/backend/src/core/activitypub/ApRendererService.ts
@@ -23,7 +23,7 @@ import { MfmService, type Appender } from '@/core/MfmService.js';
 import { UserEntityService } from '@/core/entities/UserEntityService.js';
 import { DriveFileEntityService } from '@/core/entities/DriveFileEntityService.js';
 import type { MiUserKeypair } from '@/models/UserKeypair.js';
-import type { UsersRepository, UserProfilesRepository, NotesRepository, DriveFilesRepository, PollsRepository, MiMeta } from '@/models/_.js';
+import type { UsersRepository, UserProfilesRepository, NotesRepository, DriveFilesRepository, PollsRepository, MiMeta, MiChatMessage } from '@/models/_.js';
 import { bindThis } from '@/decorators.js';
 import { CustomEmojiService } from '@/core/CustomEmojiService.js';
 import { IdService } from '@/core/IdService.js';
@@ -502,6 +502,31 @@ export class ApRendererService {
 		};
 	}
 
+	@bindThis
+	public async renderChatMessage(message: MiChatMessage, dive = true): Promise<IPost> {
+		const attributedTo = this.userEntityService.genLocalUserUri(message.fromUserId);
+
+		const file = message.fileId ? await this.driveFilesRepository.findOneBy({ id: message.fileId }) : null;
+
+		const emojis = await this.getEmojis(message.emojis);
+		const apemojis = emojis.filter(emoji => !emoji.localOnly).map(emoji => this.renderEmoji(emoji));
+
+		const tag = [
+			...apemojis,
+		];
+
+		return {
+			id: `${this.config.url}/chat-messages/${message.id}`,
+			type: 'Misskey:ChatMessage',
+			attributedTo,
+			text: message.text,
+			published: this.idService.parse(message.id).date.toISOString(),
+			to: message.toUserId,
+			attachment: file ? [this.renderDocument(file)] : [],
+			tag,
+		};
+	}
+
 	@bindThis
 	public async renderPerson(user: MiLocalUser) {
 		const id = this.userEntityService.genLocalUserUri(user.id);
diff --git a/packages/backend/src/models/ChatMessage.ts b/packages/backend/src/models/ChatMessage.ts
index 3d2b64268e..ca647efee9 100644
--- a/packages/backend/src/models/ChatMessage.ts
+++ b/packages/backend/src/models/ChatMessage.ts
@@ -55,6 +55,8 @@ export class MiChatMessage {
 	})
 	public text: string | null;
 
+	// 連合用
+	// ローカルはnull
 	@Column('varchar', {
 		length: 512, nullable: true,
 	})
@@ -82,4 +84,22 @@ export class MiChatMessage {
 		length: 1024, array: true, default: '{}',
 	})
 	public reactions: string[];
+
+	// 連合用
+	@Column('varchar', {
+		length: 128, array: true, default: '{}',
+	})
+	public emojis: string[];
+
+	// 連合用
+	@Column('boolean', {
+		default: false,
+	})
+	public isDelivering: boolean;
+
+	// 連合用
+	@Column('boolean', {
+		default: false,
+	})
+	public isDeliverFailed: boolean;
 }