diff --git a/BE/src/stock/order/stock-order-socket.service.ts b/BE/src/stock/order/stock-order-socket.service.ts
index 0f56140f..6e2bec3b 100644
--- a/BE/src/stock/order/stock-order-socket.service.ts
+++ b/BE/src/stock/order/stock-order-socket.service.ts
@@ -89,7 +89,7 @@ export class StockOrderSocketService {
 
     const totalPrice = order.price * order.amount;
     const fee = this.calculateFee(totalPrice);
-    await this.stockOrderRepository.updateOrderAndAssetWhenBuy(
+    await this.stockOrderRepository.updateOrderAndAssetAndUserStockWhenBuy(
       order,
       totalPrice + fee,
     );
@@ -100,7 +100,7 @@ export class StockOrderSocketService {
 
     const totalPrice = order.price * order.amount;
     const fee = this.calculateFee(totalPrice);
-    await this.stockOrderRepository.updateOrderAndAssetWhenSell(
+    await this.stockOrderRepository.updateOrderAndAssetAndUserStockWhenSell(
       order,
       totalPrice - fee,
     );
diff --git a/BE/src/stock/order/stock-order.module.ts b/BE/src/stock/order/stock-order.module.ts
index 454ca252..155c0855 100644
--- a/BE/src/stock/order/stock-order.module.ts
+++ b/BE/src/stock/order/stock-order.module.ts
@@ -7,9 +7,15 @@ import { StockOrderRepository } from './stock-order.repository';
 import { SocketModule } from '../../websocket/socket.module';
 import { AssetModule } from '../../asset/asset.module';
 import { StockOrderSocketService } from './stock-order-socket.service';
+import { UserStockModule } from '../../userStock/user-stock.module';
 
 @Module({
-  imports: [TypeOrmModule.forFeature([Order]), SocketModule, AssetModule],
+  imports: [
+    TypeOrmModule.forFeature([Order]),
+    SocketModule,
+    AssetModule,
+    UserStockModule,
+  ],
   controllers: [StockOrderController],
   providers: [StockOrderService, StockOrderRepository, StockOrderSocketService],
 })
diff --git a/BE/src/stock/order/stock-order.repository.ts b/BE/src/stock/order/stock-order.repository.ts
index 88344cf2..6cd70c39 100644
--- a/BE/src/stock/order/stock-order.repository.ts
+++ b/BE/src/stock/order/stock-order.repository.ts
@@ -4,6 +4,7 @@ import { Injectable, InternalServerErrorException } from '@nestjs/common';
 import { Order } from './stock-order.entity';
 import { StatusType } from './enum/status-type';
 import { Asset } from '../../asset/asset.entity';
+import { UserStock } from '../../userStock/user-stock.entity';
 
 @Injectable()
 export class StockOrderRepository extends Repository<Order> {
@@ -17,7 +18,7 @@ export class StockOrderRepository extends Repository<Order> {
       .getRawMany();
   }
 
-  async updateOrderAndAssetWhenBuy(order, realPrice) {
+  async updateOrderAndAssetAndUserStockWhenBuy(order, realPrice) {
     const queryRunner = this.dataSource.createQueryRunner();
     await queryRunner.startTransaction();
 
@@ -32,14 +33,32 @@ export class StockOrderRepository extends Repository<Order> {
         .createQueryBuilder()
         .update(Asset)
         .set({
-          cash_balance: () => 'cash_balance - :realPrice',
-          total_asset: () => 'total_asset - :realPrice',
-          total_profit: () => 'total_profit - :realPrice',
+          cash_balance: () => `cash_balance - ${realPrice}`,
+          total_asset: () => `total_asset - ${realPrice}`,
+          total_profit: () => `total_profit - ${realPrice}`,
           total_profit_rate: () => `total_profit / 10000000`,
           last_updated: new Date(),
         })
         .where({ user_id: order.user_id })
-        .setParameter('realPrice', realPrice)
+        .execute();
+
+      await queryRunner.manager
+        .createQueryBuilder()
+        .insert()
+        .into(UserStock)
+        .values({
+          user_id: order.user_id,
+          stock_code: order.stock_code,
+          quantity: order.amount,
+          avg_price: order.price,
+        })
+        .orUpdate(
+          [
+            `quantity = quantity + ${order.amount}`,
+            `avg_price = ((avg_price * quantity + ${order.price} * ${order.amount}) / (quantity + ${order.amount}))`,
+          ],
+          ['user_id', 'stock_code'],
+        )
         .execute();
 
       await queryRunner.commitTransaction();
@@ -51,7 +70,7 @@ export class StockOrderRepository extends Repository<Order> {
     }
   }
 
-  async updateOrderAndAssetWhenSell(order, realPrice) {
+  async updateOrderAndAssetAndUserStockWhenSell(order, realPrice) {
     const queryRunner = this.dataSource.createQueryRunner();
     await queryRunner.startTransaction();
 
@@ -66,14 +85,22 @@ export class StockOrderRepository extends Repository<Order> {
         .createQueryBuilder()
         .update(Asset)
         .set({
-          cash_balance: () => 'cash_balance + :realPrice',
-          total_asset: () => 'total_asset + :realPrice',
-          total_profit: () => 'total_profit + :realPrice',
+          cash_balance: () => `cash_balance + ${realPrice}`,
+          total_asset: () => `total_asset + ${realPrice}`,
+          total_profit: () => `total_profit + ${realPrice}`,
           total_profit_rate: () => `total_profit / 10000000`,
           last_updated: new Date(),
         })
         .where({ user_id: order.user_id })
-        .setParameter('realPrice', realPrice)
+        .execute();
+
+      await queryRunner.manager
+        .createQueryBuilder()
+        .update(UserStock)
+        .set({
+          quantity: () => `quantity - ${order.amount}`,
+        })
+        .where({ user_id: order.user_id, stock_code: order.stock_code })
         .execute();
 
       await queryRunner.commitTransaction();
diff --git a/BE/src/stock/order/stock-order.service.ts b/BE/src/stock/order/stock-order.service.ts
index b558dc5e..bdbfe8ce 100644
--- a/BE/src/stock/order/stock-order.service.ts
+++ b/BE/src/stock/order/stock-order.service.ts
@@ -1,4 +1,5 @@
 import {
+  BadRequestException,
   ConflictException,
   ForbiddenException,
   Injectable,
@@ -9,12 +10,14 @@ import { StockOrderRepository } from './stock-order.repository';
 import { TradeType } from './enum/trade-type';
 import { StatusType } from './enum/status-type';
 import { StockOrderSocketService } from './stock-order-socket.service';
+import { UserStockRepository } from '../../userStock/user-stock.repository';
 
 @Injectable()
 export class StockOrderService {
   constructor(
     private readonly stockOrderRepository: StockOrderRepository,
     private readonly stockOrderSocketService: StockOrderSocketService,
+    private readonly userStockRepository: UserStockRepository,
   ) {}
 
   async buy(userId: number, stockOrderRequest: StockOrderRequestDto) {
@@ -32,6 +35,14 @@ export class StockOrderService {
   }
 
   async sell(userId: number, stockOrderRequest: StockOrderRequestDto) {
+    const userStock = await this.userStockRepository.findOneBy({
+      user_id: userId,
+      stock_code: stockOrderRequest.stock_code,
+    });
+
+    if (!userStock || userStock.quantity === 0)
+      throw new BadRequestException('주식을 매도 수만큼 가지고 있지 않습니다.');
+
     const order = this.stockOrderRepository.create({
       user_id: userId,
       stock_code: stockOrderRequest.stock_code,
diff --git a/BE/src/userStock/user-stock.controller.ts b/BE/src/userStock/user-stock.controller.ts
new file mode 100644
index 00000000..e1e4c209
--- /dev/null
+++ b/BE/src/userStock/user-stock.controller.ts
@@ -0,0 +1,6 @@
+import { Controller } from '@nestjs/common';
+import { ApiTags } from '@nestjs/swagger';
+
+@Controller('/api/userStock')
+@ApiTags('사용자 보유 주식 API')
+export class UserStockController {}
diff --git a/BE/src/userStock/user-stock.entity.ts b/BE/src/userStock/user-stock.entity.ts
new file mode 100644
index 00000000..60a1b169
--- /dev/null
+++ b/BE/src/userStock/user-stock.entity.ts
@@ -0,0 +1,27 @@
+import {
+  Column,
+  Entity,
+  PrimaryGeneratedColumn,
+  UpdateDateColumn,
+} from 'typeorm';
+
+@Entity('user_stocks')
+export class UserStock {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ nullable: false })
+  user_id: number;
+
+  @Column({ nullable: false })
+  stock_code: string;
+
+  @Column({ nullable: false })
+  quantity: number;
+
+  @Column('decimal', { nullable: false, precision: 10, scale: 5 })
+  avg_price: number;
+
+  @UpdateDateColumn()
+  last_updated: Date;
+}
diff --git a/BE/src/userStock/user-stock.module.ts b/BE/src/userStock/user-stock.module.ts
new file mode 100644
index 00000000..a6466976
--- /dev/null
+++ b/BE/src/userStock/user-stock.module.ts
@@ -0,0 +1,14 @@
+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { UserStock } from './user-stock.entity';
+import { UserStockController } from './user-stock.controller';
+import { UserStockRepository } from './user-stock.repository';
+import { UserStockService } from './user-stock.service';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([UserStock])],
+  controllers: [UserStockController],
+  providers: [UserStockRepository, UserStockService],
+  exports: [UserStockRepository],
+})
+export class UserStockModule {}
diff --git a/BE/src/userStock/user-stock.repository.ts b/BE/src/userStock/user-stock.repository.ts
new file mode 100644
index 00000000..e945a667
--- /dev/null
+++ b/BE/src/userStock/user-stock.repository.ts
@@ -0,0 +1,11 @@
+import { Injectable } from '@nestjs/common';
+import { InjectDataSource } from '@nestjs/typeorm';
+import { DataSource, Repository } from 'typeorm';
+import { UserStock } from './user-stock.entity';
+
+@Injectable()
+export class UserStockRepository extends Repository<UserStock> {
+  constructor(@InjectDataSource() private dataSource: DataSource) {
+    super(UserStock, dataSource.createEntityManager());
+  }
+}
diff --git a/BE/src/userStock/user-stock.service.ts b/BE/src/userStock/user-stock.service.ts
new file mode 100644
index 00000000..1c69dcaf
--- /dev/null
+++ b/BE/src/userStock/user-stock.service.ts
@@ -0,0 +1,4 @@
+import { Injectable } from '@nestjs/common';
+
+@Injectable()
+export class UserStockService {}