diff --git a/dictation_server/src/gateways/adb2c/adb2c.service.ts b/dictation_server/src/gateways/adb2c/adb2c.service.ts
index e7dcce6..f38f5c5 100644
--- a/dictation_server/src/gateways/adb2c/adb2c.service.ts
+++ b/dictation_server/src/gateways/adb2c/adb2c.service.ts
@@ -6,8 +6,9 @@ import { ConfigService } from '@nestjs/config';
 import axios from 'axios';
 import { Aadb2cUser, B2cMetadata, JwkSignKey } from '../../common/token';
 import { AdB2cResponse, AdB2cUser } from './types/types';
+import { isPromiseRejectedResult } from './utils/utils';
 import { Context } from '../../common/log';
-import { ADB2C_SIGN_IN_TYPE } from '../../constants';
+import { ADB2C_SIGN_IN_TYPE, MANUAL_RECOVERY_REQUIRED } from '../../constants';
 
 export type ConflictError = {
   reason: 'email';
@@ -267,12 +268,33 @@ export class AdB2cService {
     );
 
     try {
-      // 複数ユーザーを一括削除する方法が不明なため、rate limitの懸念があるのを承知のうえ単一削除の繰り返しで実装
-      // TODO 一括削除する方法が判明したら修正する
-      // https://learn.microsoft.com/en-us/graph/api/user-delete?view=graph-rest-1.0&tabs=javascript#example
-      externalIds.map(
-        async (x) => await this.graphClient.api(`users/${x}`).delete(),
+      // 複数ユーザーを一括削除する方法がないため、1人ずつで削除を行う（rate limitに大きな影響がないこと確認済）
+      const results = await Promise.allSettled(
+        externalIds.map(
+          async (x) => await this.graphClient.api(`users/${x}`).delete(),
+        ),
       );
+
+      // 失敗したプロミスを抽出
+      const failedPromises = results.filter(
+        (result) => result.status === 'rejected',
+      );
+
+      // 失敗したプロミスのエラーをログに記録
+      failedPromises.forEach((result, index) => {
+        const failedId = externalIds[index];
+        if (isPromiseRejectedResult(result)) {
+          const error = result.reason.toString();
+
+          this.logger.error(
+            `${MANUAL_RECOVERY_REQUIRED}[${context.trackingId}] Failed to delete user ${failedId}: ${error}`,
+          );
+        } else {
+          this.logger.error(
+            `${MANUAL_RECOVERY_REQUIRED}[${context.trackingId}] Failed to delete user ${failedId}`,
+          );
+        }
+      });
     } catch (e) {
       this.logger.error(`error=${e}`);
       throw e;
diff --git a/dictation_server/src/gateways/adb2c/utils/utils.ts b/dictation_server/src/gateways/adb2c/utils/utils.ts
new file mode 100644
index 0000000..1d3b4a9
--- /dev/null
+++ b/dictation_server/src/gateways/adb2c/utils/utils.ts
@@ -0,0 +1,10 @@
+export const isPromiseRejectedResult = (
+  data: unknown,
+): data is PromiseRejectedResult => {
+  return (
+    data !== null &&
+    typeof data === 'object' &&
+    'status' in data &&
+    'reason' in data
+  );
+};