diff --git a/packages/backend/src/remote/activitypub/models/note.ts b/packages/backend/src/remote/activitypub/models/note.ts
index 12b2c19972..3fcaf9dc2e 100644
--- a/packages/backend/src/remote/activitypub/models/note.ts
+++ b/packages/backend/src/remote/activitypub/models/note.ts
@@ -247,7 +247,7 @@ export async function createNote(
 	// Quote
 	let quote: Note | undefined | null;
 
-	if (note._misskey_quote || note.quoteUrl || note.quoteUri) {
+	if (note.quoteUrl || note.quoteUri) {
 		const tryResolveNote = async (
 			uri: string,
 		): Promise<
@@ -284,7 +284,7 @@ export async function createNote(
 		};
 
 		const uris = unique(
-			[note._misskey_quote, note.quoteUrl, note.quoteUri].filter(
+			[note.quoteUrl, note.quoteUri].filter(
 				(x): x is string => typeof x === "string",
 			),
 		);
@@ -310,8 +310,6 @@ export async function createNote(
 		typeof note.source?.content === "string"
 	) {
 		text = note.source.content;
-	} else if (typeof note._misskey_content !== "undefined") {
-		text = note._misskey_content;
 	} else if (typeof note.content === "string") {
 		text = htmlToMfm(note.content, note.tag);
 	}
@@ -572,8 +570,6 @@ export async function updateNote(value: string | IObject, resolver?: Resolver) {
 		typeof post.source?.content === "string"
 	) {
 		text = post.source.content;
-	} else if (typeof post._misskey_content !== "undefined") {
-		text = post._misskey_content;
 	} else if (typeof post.content === "string") {
 		text = htmlToMfm(post.content, post.tag);
 	}
diff --git a/packages/backend/src/remote/activitypub/renderer/index.ts b/packages/backend/src/remote/activitypub/renderer/index.ts
index bb5dcdfc19..69d30f9008 100644
--- a/packages/backend/src/remote/activitypub/renderer/index.ts
+++ b/packages/backend/src/remote/activitypub/renderer/index.ts
@@ -37,8 +37,6 @@ export const renderActivity = (x: any): IActivity | null => {
 					value: "schema:value",
 					// Misskey
 					misskey: "https://misskey-hub.net/ns#",
-					_misskey_content: "misskey:_misskey_content",
-					_misskey_quote: "misskey:_misskey_quote",
 					_misskey_reaction: "misskey:_misskey_reaction",
 					_misskey_votes: "misskey:_misskey_votes",
 					_misskey_talk: "misskey:_misskey_talk",
diff --git a/packages/backend/src/remote/activitypub/renderer/note.ts b/packages/backend/src/remote/activitypub/renderer/note.ts
index 2ad2fec9fb..b29246edf0 100644
--- a/packages/backend/src/remote/activitypub/renderer/note.ts
+++ b/packages/backend/src/remote/activitypub/renderer/note.ts
@@ -152,12 +152,10 @@ export default async function renderNote(
 		attributedTo,
 		summary,
 		content,
-		_misskey_content: text,
 		source: {
 			content: text,
 			mediaType: "text/x.misskeymarkdown",
 		},
-		_misskey_quote: quote,
 		quoteUri: quote,
 		quoteUrl: quote,
 		published: note.createdAt.toISOString(),
diff --git a/packages/backend/src/remote/activitypub/type.ts b/packages/backend/src/remote/activitypub/type.ts
index ecaf6d6872..2258241b65 100644
--- a/packages/backend/src/remote/activitypub/type.ts
+++ b/packages/backend/src/remote/activitypub/type.ts
@@ -134,7 +134,6 @@ export interface IPost extends IObject {
 		content: string;
 		mediaType: string;
 	};
-	_misskey_quote?: string;
 	quoteUrl?: string;
 	quoteUri?: string;
 	_misskey_talk: boolean;
@@ -146,7 +145,6 @@ export interface IQuestion extends IObject {
 		content: string;
 		mediaType: string;
 	};
-	_misskey_quote?: string;
 	quoteUrl?: string;
 	oneOf?: IQuestionChoice[];
 	anyOf?: IQuestionChoice[];