diff --git a/src/test/java/com/acquirex/AcquisitionServiceTest.java b/src/test/java/com/acquirex/AcquisitionServiceTest.java
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+++ b/src/test/java/com/acquirex/AcquisitionServiceTest.java
@@ -0,0 +1,160 @@
+package com.acquirex;
+
+import com.acquirex.domain.Acquisition;
+import com.acquirex.domain.AcquisitionStatus;
+import com.acquirex.exception.AcquisitionNotFoundException;
+import com.acquirex.exception.InvalidAcquisitionStateException;
+import com.acquirex.service.AcquisitionRequest;
+import com.acquirex.service.AcquisitionResponse;
+import com.acquirex.service.AcquisitionService;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+/**
+ * AcquisitionService 단위 테스트 - Spring Boot 3 마이그레이션 검증
+ */
+@ExtendWith(MockitoExtension.class)
+class AcquisitionServiceTest {
+
+    @Mock
+    private com.acquirex.service.AcquisitionRepository acquisitionRepository;
+
+    private AcquisitionService acquisitionService;
+    private AcquisitionRequest validRequest;
+    private Acquisition pendingAcquisition;
+
+    @BeforeEach
+    void setUp() {
+        acquisitionService = new AcquisitionService(acquisitionRepository);
+        validRequest = AcquisitionRequest.builder()
+                .merchantId("MERCHANT001")
+                .cardNumber("1234567890123456")
+                .amount(new BigDecimal("50000.00"))
+                .build();
+
+        pendingAcquisition = Acquisition.builder()
+                .id(1L).merchantId("MERCHANT001").cardNumber("123456****3456")
+                .amount(new BigDecimal("50000.00")).transactionId("TXN123456789")
+                .status(AcquisitionStatus.PENDING).createdAt(LocalDateTime.now()).build();
+    }
+
+    @Test
+    @DisplayName("매입 요청 등록 성공 - Spring Boot 3 Jakarta Validation")
+    void registerAcquisition_Success() {
+        when(acquisitionRepository.save(any(Acquisition.class))).thenAnswer(invocation -> {
+            Acquisition saved = invocation.getArgument(0);
+            saved.setId(1L);
+            saved.setCreatedAt(LocalDateTime.now());
+            return saved;
+        });
+
+        AcquisitionResponse response = acquisitionService.registerAcquisition(validRequest);
+
+        assertThat(response).isNotNull();
+        assertThat(response.getMerchantId()).isEqualTo("MERCHANT001");
+        assertThat(response.getAmount()).isEqualByComparingTo(new BigDecimal("50000.00"));
+        assertThat(response.getStatus()).isEqualTo(AcquisitionStatus.PENDING);
+        assertThat(response.getCardNumber()).isEqualTo("123456****3456");
+        verify(acquisitionRepository, times(1)).save(any(Acquisition.class));
+    }
+
+    @Test
+    @DisplayName("매입 승인 처리 성공 - Spring Boot 3 @Transactional")
+    void approveAcquisition_Success() {
+        when(acquisitionRepository.findByTransactionId("TXN123456789")).thenReturn(Optional.of(pendingAcquisition));
+        when(acquisitionRepository.save(any(Acquisition.class))).thenAnswer(invocation -> invocation.getArgument(0));
+
+        AcquisitionResponse response = acquisitionService.approveAcquisition("TXN123456789");
+
+        assertThat(response).isNotNull();
+        assertThat(response.getStatus()).isEqualTo(AcquisitionStatus.APPROVED);
+        assertThat(response.getApprovalCode()).isNotNull();
+        assertThat(response.getApprovalCode()).hasSize(6);
+    }
+
+    @Test
+    @DisplayName("매입 승인 실패 - 매입 정보 없음")
+    void approveAcquisition_NotFound() {
+        when(acquisitionRepository.findByTransactionId("INVALID_TXN")).thenReturn(Optional.empty());
+
+        assertThatThrownBy(() -> acquisitionService.approveAcquisition("INVALID_TXN"))
+                .isInstanceOf(AcquisitionNotFoundException.class)
+                .hasMessageContaining("INVALID_TXN");
+    }
+
+    @Test
+    @DisplayName("매입 승인 실패 - 이미 승인된 매입")
+    void approveAcquisition_AlreadyApproved() {
+        pendingAcquisition.setStatus(AcquisitionStatus.APPROVED);
+        when(acquisitionRepository.findByTransactionId("TXN123456789")).thenReturn(Optional.of(pendingAcquisition));
+
+        assertThatThrownBy(() -> acquisitionService.approveAcquisition("TXN123456789"))
+                .isInstanceOf(InvalidAcquisitionStateException.class)
+                .hasMessageContaining("APPROVED");
+    }
+
+    @Test
+    @DisplayName("매입 거절 처리 성공")
+    void rejectAcquisition_Success() {
+        when(acquisitionRepository.findByTransactionId("TXN123456789")).thenReturn(Optional.of(pendingAcquisition));
+        when(acquisitionRepository.save(any(Acquisition.class))).thenAnswer(invocation -> invocation.getArgument(0));
+
+        AcquisitionResponse response = acquisitionService.rejectAcquisition("TXN123456789", "한도 초과");
+
+        assertThat(response).isNotNull();
+        assertThat(response.getStatus()).isEqualTo(AcquisitionStatus.REJECTED);
+    }
+
+    @Test
+    @DisplayName("매입 정보 조회 성공")
+    void getAcquisition_Success() {
+        when(acquisitionRepository.findByTransactionId("TXN123456789")).thenReturn(Optional.of(pendingAcquisition));
+
+        AcquisitionResponse response = acquisitionService.getAcquisition("TXN123456789");
+
+        assertThat(response).isNotNull();
+        assertThat(response.getTransactionId()).isEqualTo("TXN123456789");
+    }
+
+    @Test
+    @DisplayName("가맹점별 매입 목록 조회 성공")
+    void getAcquisitionsByMerchant_Success() {
+        Acquisition acquisition2 = Acquisition.builder()
+                .id(2L).merchantId("MERCHANT001").cardNumber("987654****3210")
+                .amount(new BigDecimal("30000.00")).transactionId("TXN987654321")
+                .status(AcquisitionStatus.PENDING).createdAt(LocalDateTime.now()).build();
+
+        when(acquisitionRepository.findByMerchantId("MERCHANT001")).thenReturn(Arrays.asList(pendingAcquisition, acquisition2));
+
+        List<AcquisitionResponse> responses = acquisitionService.getAcquisitionsByMerchant("MERCHANT001");
+
+        assertThat(responses).hasSize(2);
+        assertThat(responses).extracting(AcquisitionResponse::getMerchantId).containsOnly("MERCHANT001");
+    }
+
+    @Test
+    @DisplayName("대기 중인 매입 목록 조회 성공")
+    void getPendingAcquisitions_Success() {
+        when(acquisitionRepository.findByStatus(AcquisitionStatus.PENDING)).thenReturn(Arrays.asList(pendingAcquisition));
+
+        List<AcquisitionResponse> responses = acquisitionService.getPendingAcquisitions();
+
+        assertThat(responses).hasSize(1);
+        assertThat(responses.get(0).getStatus()).isEqualTo(AcquisitionStatus.PENDING);
+    }
+}
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