diff --git a/packages/backend/src/server/api/endpoints/i/update.ts b/packages/backend/src/server/api/endpoints/i/update.ts
index 3c5b02d4bb..b03528289d 100644
--- a/packages/backend/src/server/api/endpoints/i/update.ts
+++ b/packages/backend/src/server/api/endpoints/i/update.ts
@@ -479,14 +479,14 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 
 			//#region 変更されていないプロパティを削除
 			const _updates = getObjKeys(updates).reduce<Partial<MiUser>>((acc, key) => {
-				if (updates[key] != null && updates[key] !== user[key]) {
+				if (updates[key] !== undefined && updates[key] !== user[key]) {
 					(acc[key] as MiUser[typeof key]) = updates[key];
 				}
 				return acc;
 			}, {});
 
 			const _profileUpdates = getObjKeys(profileUpdates).reduce<Partial<MiUserProfile>>((acc, key) => {
-				if (profileUpdates[key] != null && profileUpdates[key] !== profile[key]) {
+				if (profileUpdates[key] !== undefined && profileUpdates[key] !== profile[key]) {
 					(acc[key] as MiUserProfile[typeof key]) = profileUpdates[key];
 				}
 				return acc;