diff --git a/packages/backend/src/core/FederatedInstanceService.ts b/packages/backend/src/core/FederatedInstanceService.ts
index 2c6d3ac50..bc66591bc 100644
--- a/packages/backend/src/core/FederatedInstanceService.ts
+++ b/packages/backend/src/core/FederatedInstanceService.ts
@@ -1,7 +1,8 @@
 import { Inject, Injectable } from '@nestjs/common';
+import Redis from 'ioredis';
 import type { InstancesRepository } from '@/models/index.js';
 import type { Instance } from '@/models/entities/Instance.js';
-import { MemoryKVCache } from '@/misc/cache.js';
+import { MemoryKVCache, RedisKVCache } from '@/misc/cache.js';
 import { IdService } from '@/core/IdService.js';
 import { DI } from '@/di-symbols.js';
 import { UtilityService } from '@/core/UtilityService.js';
@@ -9,23 +10,32 @@ import { bindThis } from '@/decorators.js';
 
 @Injectable()
 export class FederatedInstanceService {
-	private cache: MemoryKVCache<Instance>;
+	public federatedInstanceCache: RedisKVCache<Instance | null>;
 
 	constructor(
+		@Inject(DI.redis)
+		private redisClient: Redis.Redis,
+
 		@Inject(DI.instancesRepository)
 		private instancesRepository: InstancesRepository,
 
 		private utilityService: UtilityService,
 		private idService: IdService,
 	) {
-		this.cache = new MemoryKVCache<Instance>(1000 * 60 * 60);
+		this.federatedInstanceCache = new RedisKVCache<Instance | null>(this.redisClient, 'federatedInstance', {
+			lifetime: 1000 * 60 * 60 * 24, // 24h
+			memoryCacheLifetime: 1000 * 60 * 30, // 30m
+			fetcher: (key) => this.instancesRepository.findOneBy({ host: key }),
+			toRedisConverter: (value) => JSON.stringify(value),
+			fromRedisConverter: (value) => JSON.parse(value), // TODO: date型の考慮
+		});
 	}
 
 	@bindThis
 	public async fetch(host: string): Promise<Instance> {
 		host = this.utilityService.toPuny(host);
 	
-		const cached = this.cache.get(host);
+		const cached = await this.federatedInstanceCache.get(host);
 		if (cached) return cached;
 	
 		const index = await this.instancesRepository.findOneBy({ host });
@@ -37,10 +47,10 @@ export class FederatedInstanceService {
 				firstRetrievedAt: new Date(),
 			}).then(x => this.instancesRepository.findOneByOrFail(x.identifiers[0]));
 	
-			this.cache.set(host, i);
+			this.federatedInstanceCache.set(host, i);
 			return i;
 		} else {
-			this.cache.set(host, index);
+			this.federatedInstanceCache.set(host, index);
 			return index;
 		}
 	}
@@ -49,10 +59,10 @@ export class FederatedInstanceService {
 	public async updateCachePartial(host: string, data: Partial<Instance>): Promise<void> {
 		host = this.utilityService.toPuny(host);
 	
-		const cached = this.cache.get(host);
+		const cached = await this.federatedInstanceCache.get(host);
 		if (cached == null) return;
 	
-		this.cache.set(host, {
+		this.federatedInstanceCache.set(host, {
 			...cached,
 			...data,
 		});
diff --git a/packages/backend/src/core/entities/UserEntityService.ts b/packages/backend/src/core/entities/UserEntityService.ts
index d964b1b1b..cbe94451c 100644
--- a/packages/backend/src/core/entities/UserEntityService.ts
+++ b/packages/backend/src/core/entities/UserEntityService.ts
@@ -9,13 +9,13 @@ import type { Packed } from '@/misc/json-schema.js';
 import type { Promiseable } from '@/misc/prelude/await-all.js';
 import { awaitAll } from '@/misc/prelude/await-all.js';
 import { USER_ACTIVE_THRESHOLD, USER_ONLINE_THRESHOLD } from '@/const.js';
-import { MemoryKVCache, RedisKVCache } from '@/misc/cache.js';
 import type { Instance } from '@/models/entities/Instance.js';
 import type { LocalUser, RemoteUser, User } from '@/models/entities/User.js';
 import { birthdaySchema, descriptionSchema, localUsernameSchema, locationSchema, nameSchema, passwordSchema } from '@/models/entities/User.js';
 import type { UsersRepository, UserSecurityKeysRepository, FollowingsRepository, FollowRequestsRepository, BlockingsRepository, MutingsRepository, DriveFilesRepository, NoteUnreadsRepository, ChannelFollowingsRepository, UserNotePiningsRepository, UserProfilesRepository, InstancesRepository, AnnouncementReadsRepository, AnnouncementsRepository, PagesRepository, UserProfile, RenoteMutingsRepository } from '@/models/index.js';
 import { bindThis } from '@/decorators.js';
 import { RoleService } from '@/core/RoleService.js';
+import { FederatedInstanceService } from '@/core/FederatedInstanceService.js';
 import type { OnModuleInit } from '@nestjs/common';
 import type { AntennaService } from '../AntennaService.js';
 import type { CustomEmojiService } from '../CustomEmojiService.js';
@@ -53,7 +53,7 @@ export class UserEntityService implements OnModuleInit {
 	private customEmojiService: CustomEmojiService;
 	private antennaService: AntennaService;
 	private roleService: RoleService;
-	private userInstanceCache: RedisKVCache<Instance | null>;
+	private federatedInstanceService: FederatedInstanceService;
 
 	constructor(
 		private moduleRef: ModuleRef,
@@ -119,13 +119,6 @@ export class UserEntityService implements OnModuleInit {
 		//private antennaService: AntennaService,
 		//private roleService: RoleService,
 	) {
-		this.userInstanceCache = new RedisKVCache<Instance | null>(this.redisClient, 'userInstance', {
-			lifetime: 1000 * 60 * 60 * 24, // 24h
-			memoryCacheLifetime: 1000 * 60 * 30, // 30m
-			fetcher: (key) => this.instancesRepository.findOneBy({ host: key }),
-			toRedisConverter: (value) => JSON.stringify(value),
-			fromRedisConverter: (value) => JSON.parse(value), // TODO: date型の考慮
-		});
 	}
 
 	onModuleInit() {
@@ -135,6 +128,7 @@ export class UserEntityService implements OnModuleInit {
 		this.customEmojiService = this.moduleRef.get('CustomEmojiService');
 		this.antennaService = this.moduleRef.get('AntennaService');
 		this.roleService = this.moduleRef.get('RoleService');
+		this.federatedInstanceService = this.moduleRef.get('FederatedInstanceService');
 	}
 
 	//#region Validators
@@ -349,7 +343,7 @@ export class UserEntityService implements OnModuleInit {
 			avatarBlurhash: user.avatarBlurhash,
 			isBot: user.isBot ?? falsy,
 			isCat: user.isCat ?? falsy,
-			instance: user.host ? this.userInstanceCache.fetch(user.host).then(instance => instance ? {
+			instance: user.host ? this.federatedInstanceService.federatedInstanceCache.fetch(user.host).then(instance => instance ? {
 				name: instance.name,
 				softwareName: instance.softwareName,
 				softwareVersion: instance.softwareVersion,