diff --git a/BE/src/auth/users.repository.ts b/BE/src/auth/users.repository.ts
index 2482edb..89cd62b 100644
--- a/BE/src/auth/users.repository.ts
+++ b/BE/src/auth/users.repository.ts
@@ -42,4 +42,9 @@ export class UsersRepository {
   async getUserByUserId(userId: string): Promise<User | null> {
     return User.findOne({ where: { userId } });
   }
+
+  async accrueCredits(user: User, amount: number): Promise<void> {
+    user.credit += amount;
+    await user.save();
+  }
 }
diff --git a/BE/src/diaries/diaries.module.ts b/BE/src/diaries/diaries.module.ts
index 8a9dd4e..2f8df0e 100644
--- a/BE/src/diaries/diaries.module.ts
+++ b/BE/src/diaries/diaries.module.ts
@@ -11,6 +11,7 @@ import { ShapesRepository } from "src/shapes/shapes.repository";
 import { TagsRepository } from "src/tags/tags.repository";
 import { HttpModule } from "@nestjs/axios";
 import { Line } from "src/lines/lines.entity";
+import { UsersRepository } from "src/auth/users.repository";
 
 @Module({
   imports: [
@@ -26,6 +27,7 @@ import { Line } from "src/lines/lines.entity";
     DiariesRepository,
     TagsRepository,
     ShapesRepository,
+    UsersRepository,
   ],
 })
 export class DiariesModule {}
diff --git a/BE/src/diaries/diaries.repository.ts b/BE/src/diaries/diaries.repository.ts
index 468bc62..dd68bf7 100644
--- a/BE/src/diaries/diaries.repository.ts
+++ b/BE/src/diaries/diaries.repository.ts
@@ -12,6 +12,7 @@ import { NotFoundException } from "@nestjs/common";
 import { Tag } from "src/tags/tags.entity";
 import { ReadDiaryDto } from "./dto/diaries.read.dto";
 import { SentimentDto } from "./dto/diaries.sentiment.dto";
+import { Between } from "typeorm";
 
 export class DiariesRepository {
   async createDiary(
@@ -120,4 +121,22 @@ export class DiariesRepository {
 
     return found;
   }
+
+  async getDiaryByToday(userId: string): Promise<Diary[]> {
+    const currentDate = new Date();
+    const [year, month, date] = [
+      currentDate.getFullYear(),
+      currentDate.getMonth(),
+      currentDate.getDate(),
+    ];
+    const startDate = new Date(year, month, date, 0, 0, 0, 0);
+    const endDate = new Date(year, month, date, 23, 59, 59, 999);
+
+    const diaryList = await Diary.find({
+      where: { user: { userId }, createdDate: Between(startDate, endDate) },
+      withDeleted: true,
+    });
+
+    return diaryList;
+  }
 }
diff --git a/BE/src/diaries/diaries.service.ts b/BE/src/diaries/diaries.service.ts
index d973a64..988a5e9 100644
--- a/BE/src/diaries/diaries.service.ts
+++ b/BE/src/diaries/diaries.service.ts
@@ -16,10 +16,12 @@ import { ShapesRepository } from "src/shapes/shapes.repository";
 import { HttpService } from "@nestjs/axios";
 import { lastValueFrom } from "rxjs";
 import { sentimentStatus } from "src/utils/enum";
+import { UsersRepository } from "src/auth/users.repository";
 
 @Injectable()
 export class DiariesService {
   constructor(
+    private usersRepository: UsersRepository,
     private diariesRepository: DiariesRepository,
     private tagsRepository: TagsRepository,
     private shapesRepository: ShapesRepository,
@@ -33,6 +35,12 @@ export class DiariesService {
     const encryptedContent = await this.getEncryptedContent(trimContent);
     const tagEntities = await this.getTags(tags);
     const sentimentResult: SentimentDto = await this.getSentiment(trimContent);
+
+    const WRITE_REWARD_CREDIT = 30;
+    if (await this.isFirstDiaryForToday(user.userId)) {
+      await this.usersRepository.accrueCredits(user, WRITE_REWARD_CREDIT);
+    }
+
     const diary = await this.diariesRepository.createDiary(
       createDiaryDto,
       encryptedContent,
@@ -45,6 +53,12 @@ export class DiariesService {
     return diary;
   }
 
+  async isFirstDiaryForToday(userId: string): Promise<boolean> {
+    const todayDiaries = await this.diariesRepository.getDiaryByToday(userId);
+
+    return todayDiaries.length === 0;
+  }
+
   async readDiary(readDiaryDto: ReadDiaryDto): Promise<Diary> {
     let diary = await this.diariesRepository.readDiary(readDiaryDto);
 
diff --git a/BE/src/purchase/purchase.controller.ts b/BE/src/purchase/purchase.controller.ts
index fbddb35..795bd75 100644
--- a/BE/src/purchase/purchase.controller.ts
+++ b/BE/src/purchase/purchase.controller.ts
@@ -18,6 +18,11 @@ import { CreditDto } from "./dto/purchase.credit.dto";
 export class PurchaseController {
   constructor(private purchaseService: PurchaseService) {}
 
+  @Get("/credit")
+  async getCreditBalanceByUser(@GetUser() user: User): Promise<CreditDto> {
+    return new CreditDto(user.credit);
+  }
+
   @Post("/design")
   async purchaseDesign(
     @GetUser() user: User,