diff --git a/packages/backend/src/config.ts b/packages/backend/src/config.ts
index 9b053a4b95..04212e35c2 100644
--- a/packages/backend/src/config.ts
+++ b/packages/backend/src/config.ts
@@ -100,6 +100,7 @@ type Source = {
 
 	bypassRateLimit?: { header: string; value: string }[];
 
+	remapDriveFileUrlForActivityPub?: { target: string; replacement: string }[];
 	signToActivityPubGet?: boolean;
 
 	perChannelMaxNoteCacheCount?: number;
@@ -160,6 +161,7 @@ export type Config = {
 	deliverJobMaxAttempts: number | undefined;
 	inboxJobMaxAttempts: number | undefined;
 	proxyRemoteFiles: boolean | undefined;
+	remapDriveFileUrlForActivityPub: { target: string; replacement: string }[] | undefined;
 	signToActivityPubGet: boolean | undefined;
 
 	version: string;
@@ -285,6 +287,7 @@ export function loadConfig(): Config {
 		deliverJobMaxAttempts: config.deliverJobMaxAttempts,
 		inboxJobMaxAttempts: config.inboxJobMaxAttempts,
 		proxyRemoteFiles: config.proxyRemoteFiles,
+		remapDriveFileUrlForActivityPub: config.remapDriveFileUrlForActivityPub,
 		signToActivityPubGet: config.signToActivityPubGet,
 		mediaProxy: externalMediaProxy ?? internalMediaProxy,
 		externalMediaProxyEnabled: externalMediaProxy !== null && externalMediaProxy !== internalMediaProxy,
diff --git a/packages/backend/src/core/activitypub/ApRendererService.ts b/packages/backend/src/core/activitypub/ApRendererService.ts
index 3a0367ba64..83169a3d3b 100644
--- a/packages/backend/src/core/activitypub/ApRendererService.ts
+++ b/packages/backend/src/core/activitypub/ApRendererService.ts
@@ -164,13 +164,20 @@ export class ApRendererService {
 		return {
 			type: 'Document',
 			mediaType: file.webpublicType ?? file.type,
-			url: this.driveFileEntityService.getPublicUrl(file),
+			url: this.driveFileEntityService.getPublicUrl(file, { remapActivityPub: true }),
 			name: file.comment,
 		};
 	}
 
 	@bindThis
 	public renderEmoji(emoji: MiEmoji): IApEmoji {
+		// || emoji.originalUrl してるのは後方互換性のため（publicUrlはstringなので??はだめ）
+		let url = emoji.publicUrl || emoji.originalUrl;
+
+		this.config.remapDriveFileUrlForActivityPub?.forEach(({ target, replacement }) => {
+			url = url.replace(target, replacement);
+		});
+
 		return {
 			id: `${this.config.url}/emojis/${emoji.name}`,
 			type: 'Emoji',
@@ -179,8 +186,7 @@ export class ApRendererService {
 			icon: {
 				type: 'Image',
 				mediaType: emoji.type ?? 'image/png',
-				// || emoji.originalUrl してるのは後方互換性のため（publicUrlはstringなので??はだめ）
-				url: emoji.publicUrl || emoji.originalUrl,
+				url: url,
 			},
 		};
 	}
@@ -243,7 +249,7 @@ export class ApRendererService {
 	public renderImage(file: MiDriveFile): IApImage {
 		return {
 			type: 'Image',
-			url: this.driveFileEntityService.getPublicUrl(file),
+			url: this.driveFileEntityService.getPublicUrl(file, { remapActivityPub: true }),
 			sensitive: file.isSensitive,
 			name: file.comment,
 		};
diff --git a/packages/backend/src/core/activitypub/models/ApPersonService.ts b/packages/backend/src/core/activitypub/models/ApPersonService.ts
index 56e4e521ed..6a3b543066 100644
--- a/packages/backend/src/core/activitypub/models/ApPersonService.ts
+++ b/packages/backend/src/core/activitypub/models/ApPersonService.ts
@@ -267,12 +267,12 @@ export class ApPersonService implements OnModuleInit {
 		return {
 			...( avatar ? {
 				avatarId: avatar.id,
-				avatarUrl: avatar.url ? this.driveFileEntityService.getPublicUrl(avatar, 'avatar') : null,
+				avatarUrl: avatar.url ? this.driveFileEntityService.getPublicUrl(avatar, { mode: 'avatar', remapActivityPub: true }) : null,
 				avatarBlurhash: avatar.blurhash,
 			} : {}),
 			...( banner ? {
 				bannerId: banner.id,
-				bannerUrl: banner.url ? this.driveFileEntityService.getPublicUrl(banner) : null,
+				bannerUrl: banner.url ? this.driveFileEntityService.getPublicUrl(banner, { remapActivityPub: true }) : null,
 				bannerBlurhash: banner.blurhash,
 			} : {}),
 		};
diff --git a/packages/backend/src/core/entities/DriveFileEntityService.ts b/packages/backend/src/core/entities/DriveFileEntityService.ts
index 6f8f5797a1..75e4dda505 100644
--- a/packages/backend/src/core/entities/DriveFileEntityService.ts
+++ b/packages/backend/src/core/entities/DriveFileEntityService.ts
@@ -109,10 +109,10 @@ export class DriveFileEntityService {
 	}
 
 	@bindThis
-	public getPublicUrl(file: MiDriveFile, mode?: 'avatar'): string { // static = thumbnail
+	public getPublicUrl(file: MiDriveFile, option?: { mode?: 'avatar', remapActivityPub?: boolean }): string { // static = thumbnail
 		// リモートかつメディアプロキシ
 		if (file.uri != null && file.userHost != null && this.config.externalMediaProxyEnabled) {
-			return this.getProxiedUrl(file.uri, mode);
+			return this.getProxiedUrl(file.uri, option?.mode);
 		}
 
 		// リモートかつ期限切れはローカルプロキシを試みる
@@ -121,17 +121,23 @@ export class DriveFileEntityService {
 
 			if (key && !key.match('/')) {	// 古いものはここにオブジェクトストレージキーが入ってるので除外
 				const url = `${this.config.url}/files/${key}`;
-				if (mode === 'avatar') return this.getProxiedUrl(file.uri, 'avatar');
+				if (option?.mode === 'avatar') return this.getProxiedUrl(file.uri, 'avatar');
 				return url;
 			}
 		}
 
-		const url = file.webpublicUrl ?? file.url;
-
-		if (mode === 'avatar') {
-			return this.getProxiedUrl(url, 'avatar');
+		let publicUrl = file.webpublicUrl ?? file.url;
+		if (option?.remapActivityPub) {
+			this.config.remapDriveFileUrlForActivityPub?.forEach(({ target, replacement }) => {
+				publicUrl = publicUrl.replace(target, replacement);
+			});
 		}
-		return url;
+
+		const url = new URL(publicUrl);
+		if (file.isSensitive) url.searchParams.set('sensitive', 'true');
+
+		if (option?.mode === 'avatar') return this.getProxiedUrl(url.href, 'avatar');
+		else return url.href;
 	}
 
 	@bindThis
diff --git a/packages/backend/src/server/api/endpoints/i/update.ts b/packages/backend/src/server/api/endpoints/i/update.ts
index 5e64511f72..5ff035ec4a 100644
--- a/packages/backend/src/server/api/endpoints/i/update.ts
+++ b/packages/backend/src/server/api/endpoints/i/update.ts
@@ -314,7 +314,7 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 				if (!avatar.type.startsWith('image/')) throw new ApiError(meta.errors.avatarNotAnImage);
 
 				updates.avatarId = avatar.id;
-				updates.avatarUrl = this.driveFileEntityService.getPublicUrl(avatar, 'avatar');
+				updates.avatarUrl = this.driveFileEntityService.getPublicUrl(avatar, { mode: 'avatar' });
 				updates.avatarBlurhash = avatar.blurhash;
 			} else if (ps.avatarId === null) {
 				updates.avatarId = null;