diff --git a/packages/backend/src/remote/activitypub/renderer/note.ts b/packages/backend/src/remote/activitypub/renderer/note.ts
index b29246edf..edeeb4222 100644
--- a/packages/backend/src/remote/activitypub/renderer/note.ts
+++ b/packages/backend/src/remote/activitypub/renderer/note.ts
@@ -1,4 +1,5 @@
 import { In, IsNull } from "typeorm";
+import { detect as detectLanguage } from "tinyld";
 import config from "@/config/index.js";
 import type { Note, IMentionedRemoteUsers } from "@/models/entities/note.js";
 import type { DriveFile } from "@/models/entities/drive-file.js";
@@ -114,6 +115,11 @@ export default async function renderNote(
 		}),
 	);
 
+	const lang = detectLanguage(text);
+	const contentMap = lang ? {
+		[lang]: content
+	} : null;
+
 	const emojis = await getEmojis(note.emojis);
 	const apemojis = emojis.map((emoji) => renderEmoji(emoji));
 
@@ -152,6 +158,7 @@ export default async function renderNote(
 		attributedTo,
 		summary,
 		content,
+		contentMap,
 		source: {
 			content: text,
 			mediaType: "text/x.misskeymarkdown",
diff --git a/packages/backend/src/remote/activitypub/type.ts b/packages/backend/src/remote/activitypub/type.ts
index 2258241b6..0e63f3ed5 100644
--- a/packages/backend/src/remote/activitypub/type.ts
+++ b/packages/backend/src/remote/activitypub/type.ts
@@ -14,6 +14,7 @@ export interface IObject {
 	inReplyTo?: any;
 	replies?: ICollection;
 	content?: string;
+	contentMap?: obj;
 	name?: string;
 	startTime?: Date;
 	endTime?: Date;