diff --git a/packages/backend/src/mfm/from-html.ts b/packages/backend/src/mfm/from-html.ts
index 33bbb66f4..9b4346d2c 100644
--- a/packages/backend/src/mfm/from-html.ts
+++ b/packages/backend/src/mfm/from-html.ts
@@ -1,11 +1,12 @@
 import { URL } from "node:url";
 import * as parse5 from "parse5";
 import { defaultTreeAdapter as treeAdapter } from "parse5";
+import { getSubjectHostFromUriAndUsernameCached } from "@/remote/resolve-user.js";
 
 const urlRegex = /^https?:\/\/[\w\/:%#@$&?!()\[\]~.,=+\-]+/;
 const urlRegexFull = /^https?:\/\/[\w\/:%#@$&?!()\[\]~.,=+\-]+$/;
 
-export async function fromHtml(html: string, hashtagNames?: string[]): Promise<string> {
+export async function fromHtml(html: string, hashtagNames?: string[], basicMentionResolve: boolean = false): Promise<string> {
 	// some AP servers like Pixelfed use br tags as well as newlines
 	html = html.replace(/<br\s?\/?>\r?\n/gi, "\n");
 
@@ -72,7 +73,9 @@ export async function fromHtml(html: string, hashtagNames?: string[]): Promise<s
 
 					if (part.length === 2 && href) {
 						//#region ホスト名部分が省略されているので復元する
-						const acct = `${txt}@${new URL(href.value).hostname}`;
+						const acct = basicMentionResolve
+							? `${txt}@${new URL(href.value).hostname}`
+							: `${txt}@${await getSubjectHostFromUriAndUsernameCached(href.value, txt)}`;
 						text += acct;
 						//#endregion
 					} else if (part.length === 3) {
diff --git a/packages/backend/src/remote/resolve-user.ts b/packages/backend/src/remote/resolve-user.ts
index f6d6b2dfe..a75c810df 100644
--- a/packages/backend/src/remote/resolve-user.ts
+++ b/packages/backend/src/remote/resolve-user.ts
@@ -187,6 +187,22 @@ export async function getSubjectHostFromUri(uri: string): Promise<string | null>
 	}
 }
 
+export async function getSubjectHostFromUriAndUsernameCached(uri: string, username: string): Promise<string | null> {
+	const hostname = new URL(uri).hostname;
+	username = username.substring(1); // remove leading @ from username
+
+	const user = await Users.findOneBy({
+		usernameLower: username.toLowerCase(),
+		host: hostname
+	});
+
+	if (user) {
+		return user.host;
+	}
+
+	return await getSubjectHostFromUri(uri) ?? hostname;
+}
+
 export async function getSubjectHostFromAcct(acct: string): Promise<string | null> {
 	try {
 		const res = await resolveUserWebFinger(acct.toLowerCase());
diff --git a/packages/backend/test/mfm.ts b/packages/backend/test/mfm.ts
index 6b7d5fb1b..5c9250048 100644
--- a/packages/backend/test/mfm.ts
+++ b/packages/backend/test/mfm.ts
@@ -111,6 +111,8 @@ describe("fromHtml", () => {
 		assert.deepStrictEqual(
 			await fromHtml(
 				'<p>a <a href="https://joiniceshrimp.org/@user" class="u-url mention">@user</a> d</p>',
+				undefined,
+				false
 			),
 			"a @user@joiniceshrimp.org d",
 		);