diff --git a/packages/backend/src/core/WebhookTestService.ts b/packages/backend/src/core/WebhookTestService.ts
index 222153fd2a..9cf985b688 100644
--- a/packages/backend/src/core/WebhookTestService.ts
+++ b/packages/backend/src/core/WebhookTestService.ts
@@ -411,8 +411,8 @@ export class WebhookTestService {
 			name: user.name,
 			username: user.username,
 			host: user.host,
-			avatarUrl: user.avatarUrl,
-			avatarBlurhash: user.avatarBlurhash,
+			avatarUrl: user.avatarId == null ? null : user.avatarUrl,
+			avatarBlurhash: user.avatarId == null ? null : user.avatarBlurhash,
 			avatarDecorations: user.avatarDecorations.map(it => ({
 				id: it.id,
 				angle: it.angle,
@@ -441,8 +441,8 @@ export class WebhookTestService {
 			createdAt: new Date().toISOString(),
 			updatedAt: user.updatedAt?.toISOString() ?? null,
 			lastFetchedAt: user.lastFetchedAt?.toISOString() ?? null,
-			bannerUrl: user.bannerUrl,
-			bannerBlurhash: user.bannerBlurhash,
+			bannerUrl: user.bannerId == null ? null : user.bannerUrl,
+			bannerBlurhash: user.bannerId == null ? null : user.bannerBlurhash,
 			isLocked: user.isLocked,
 			isSilenced: false,
 			isSuspended: user.isSuspended,
diff --git a/packages/backend/src/core/entities/UserEntityService.ts b/packages/backend/src/core/entities/UserEntityService.ts
index e252ff509e..d4769d24d4 100644
--- a/packages/backend/src/core/entities/UserEntityService.ts
+++ b/packages/backend/src/core/entities/UserEntityService.ts
@@ -486,8 +486,8 @@ export class UserEntityService implements OnModuleInit {
 			name: user.name,
 			username: user.username,
 			host: user.host,
-			avatarUrl: user.avatarUrl ?? this.getIdenticonUrl(user),
-			avatarBlurhash: user.avatarBlurhash,
+			avatarUrl: (user.avatarId == null ? null : user.avatarUrl) ?? this.getIdenticonUrl(user),
+			avatarBlurhash: (user.avatarId == null ? null : user.avatarBlurhash),
 			avatarDecorations: user.avatarDecorations.length > 0 ? this.avatarDecorationService.getAll().then(decorations => user.avatarDecorations.filter(ud => decorations.some(d => d.id === ud.id)).map(ud => ({
 				id: ud.id,
 				angle: ud.angle || undefined,
@@ -533,8 +533,8 @@ export class UserEntityService implements OnModuleInit {
 				createdAt: this.idService.parse(user.id).date.toISOString(),
 				updatedAt: user.updatedAt ? user.updatedAt.toISOString() : null,
 				lastFetchedAt: user.lastFetchedAt ? user.lastFetchedAt.toISOString() : null,
-				bannerUrl: user.bannerUrl,
-				bannerBlurhash: user.bannerBlurhash,
+				bannerUrl: user.bannerId == null ? null : user.bannerUrl,
+				bannerBlurhash: user.bannerId == null ? null : user.bannerBlurhash,
 				isLocked: user.isLocked,
 				isSilenced: this.roleService.getUserPolicies(user.id).then(r => !r.canPublicNote),
 				isSuspended: user.isSuspended,
diff --git a/packages/backend/src/models/User.ts b/packages/backend/src/models/User.ts
index bc652cea62..baf4eefdf1 100644
--- a/packages/backend/src/models/User.ts
+++ b/packages/backend/src/models/User.ts
@@ -118,21 +118,25 @@ export class MiUser {
 	@JoinColumn()
 	public banner: MiDriveFile | null;
 
+	// avatarId が null になったとしてもこれが null でない可能性があるため、このフィールドを使うときは avatarId の non-null チェックをすること
 	@Column('varchar', {
 		length: 512, nullable: true,
 	})
 	public avatarUrl: string | null;
 
+	// bannerId が null になったとしてもこれが null でない可能性があるため、このフィールドを使うときは bannerId の non-null チェックをすること
 	@Column('varchar', {
 		length: 512, nullable: true,
 	})
 	public bannerUrl: string | null;
 
+	// avatarId が null になったとしてもこれが null でない可能性があるため、このフィールドを使うときは avatarId の non-null チェックをすること
 	@Column('varchar', {
 		length: 128, nullable: true,
 	})
 	public avatarBlurhash: string | null;
 
+	// bannerId が null になったとしてもこれが null でない可能性があるため、このフィールドを使うときは bannerId の non-null チェックをすること
 	@Column('varchar', {
 		length: 128, nullable: true,
 	})
diff --git a/packages/backend/src/server/ServerService.ts b/packages/backend/src/server/ServerService.ts
index b899053287..355d7ca08e 100644
--- a/packages/backend/src/server/ServerService.ts
+++ b/packages/backend/src/server/ServerService.ts
@@ -221,7 +221,7 @@ export class ServerService implements OnApplicationShutdown {
 			reply.header('Cache-Control', 'public, max-age=86400');
 
 			if (user) {
-				reply.redirect(user.avatarUrl ?? this.userEntityService.getIdenticonUrl(user));
+				reply.redirect((user.avatarId == null ? null : user.avatarUrl) ?? this.userEntityService.getIdenticonUrl(user));
 			} else {
 				reply.redirect('/static-assets/user-unknown.png');
 			}
diff --git a/packages/backend/src/server/web/ClientServerService.ts b/packages/backend/src/server/web/ClientServerService.ts
index 927970e2e2..30a911088e 100644
--- a/packages/backend/src/server/web/ClientServerService.ts
+++ b/packages/backend/src/server/web/ClientServerService.ts
@@ -534,7 +534,7 @@ export class ClientServerService {
 
 				return await reply.view('user', {
 					user, profile, me,
-					avatarUrl: user.avatarUrl ?? this.userEntityService.getIdenticonUrl(user),
+					avatarUrl: _user.avatarUrl,
 					sub: request.params.sub,
 					...await this.generateCommonPugData(this.meta),
 					clientCtx: htmlSafeJsonStringify({
diff --git a/packages/backend/src/server/web/FeedService.ts b/packages/backend/src/server/web/FeedService.ts
index 9d810ddc84..eae7645321 100644
--- a/packages/backend/src/server/web/FeedService.ts
+++ b/packages/backend/src/server/web/FeedService.ts
@@ -65,7 +65,7 @@ export class FeedService {
 			generator: 'Misskey',
 			description: `${user.notesCount} Notes, ${profile.followingVisibility === 'public' ? user.followingCount : '?'} Following, ${profile.followersVisibility === 'public' ? user.followersCount : '?'} Followers${profile.description ? ` · ${profile.description}` : ''}`,
 			link: author.link,
-			image: user.avatarUrl ?? this.userEntityService.getIdenticonUrl(user),
+			image: (user.avatarId == null ? null : user.avatarUrl) ?? this.userEntityService.getIdenticonUrl(user),
 			feedLinks: {
 				json: `${author.link}.json`,
 				atom: `${author.link}.atom`,