diff --git a/src/test/java/com/acquirex/service/AcquisitionApprovalServiceTest.java b/src/test/java/com/acquirex/service/AcquisitionApprovalServiceTest.java
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+++ b/src/test/java/com/acquirex/service/AcquisitionApprovalServiceTest.java
@@ -0,0 +1,155 @@
+package com.acquirex.service;
+
+import com.acquirex.domain.AcquisitionApproval;
+import com.acquirex.domain.AcquisitionApproval.ApprovalStatus;
+import com.acquirex.dto.ApprovalRequest;
+import com.acquirex.dto.ApprovalResponse;
+import com.acquirex.exception.ApprovalProcessingException;
+import com.acquirex.repository.AcquisitionApprovalRepository;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.math.BigDecimal;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
+class AcquisitionApprovalServiceTest {
+
+    @Mock
+    private AcquisitionApprovalRepository repository;
+
+    @InjectMocks
+    private AcquisitionApprovalService service;
+
+    private ApprovalRequest validRequest;
+    private AcquisitionApproval savedApproval;
+
+    @BeforeEach
+    void setUp() {
+        validRequest = new ApprovalRequest("MERCHANT001", "4111111111111111", new BigDecimal("100.00"), "KRW");
+
+        savedApproval = new AcquisitionApproval();
+        savedApproval.setId(1L);
+        savedApproval.setMerchantId("MERCHANT001");
+        savedApproval.setCardNumber("****-****-****-1111");
+        savedApproval.setAmount(new BigDecimal("100.00"));
+        savedApproval.setCurrency("KRW");
+        savedApproval.setStatus(ApprovalStatus.PENDING);
+    }
+
+    @Test
+    void requestApproval_ValidRequest_ReturnsApprovalResponse() {
+        when(repository.save(any(AcquisitionApproval.class))).thenReturn(savedApproval);
+
+        ApprovalResponse response = service.requestApproval(validRequest);
+
+        assertNotNull(response);
+        assertEquals(1L, response.getId());
+        assertEquals("MERCHANT001", response.getMerchantId());
+        assertEquals("PENDING", response.getStatus());
+        assertTrue(response.getCardNumber().startsWith("****"));
+        verify(repository, times(1)).save(any(AcquisitionApproval.class));
+    }
+
+    @Test
+    void requestApproval_InvalidMerchantId_ThrowsException() {
+        validRequest.setMerchantId("");
+        assertThrows(ApprovalProcessingException.class, () -> service.requestApproval(validRequest));
+    }
+
+    @Test
+    void requestApproval_InvalidAmount_ThrowsException() {
+        validRequest.setAmount(BigDecimal.ZERO);
+        assertThrows(ApprovalProcessingException.class, () -> service.requestApproval(validRequest));
+    }
+
+    @Test
+    void processApproval_Approve_UpdatesStatusToApproved() {
+        savedApproval.setStatus(ApprovalStatus.PENDING);
+        when(repository.findById(1L)).thenReturn(Optional.of(savedApproval));
+        when(repository.save(any(AcquisitionApproval.class))).thenAnswer(inv -> inv.getArgument(0));
+
+        ApprovalResponse response = service.processApproval(1L, true, null);
+
+        assertEquals("APPROVED", response.getStatus());
+        assertNotNull(response.getApprovalCode());
+        assertTrue(response.getApprovalCode().startsWith("APP-"));
+    }
+
+    @Test
+    void processApproval_Reject_UpdatesStatusToRejected() {
+        savedApproval.setStatus(ApprovalStatus.PENDING);
+        when(repository.findById(1L)).thenReturn(Optional.of(savedApproval));
+        when(repository.save(any(AcquisitionApproval.class))).thenAnswer(inv -> inv.getArgument(0));
+
+        ApprovalResponse response = service.processApproval(1L, false, "Insufficient funds");
+
+        assertEquals("REJECTED", response.getStatus());
+        assertEquals("Insufficient funds", response.getRejectionReason());
+        assertNull(response.getApprovalCode());
+    }
+
+    @Test
+    void processApproval_AlreadyProcessed_ThrowsException() {
+        savedApproval.setStatus(ApprovalStatus.APPROVED);
+        when(repository.findById(1L)).thenReturn(Optional.of(savedApproval));
+        assertThrows(ApprovalProcessingException.class, () -> service.processApproval(1L, true, null));
+    }
+
+    @Test
+    void processApproval_NotFound_ThrowsException() {
+        when(repository.findById(999L)).thenReturn(Optional.empty());
+        assertThrows(ApprovalProcessingException.class, () -> service.processApproval(999L, true, null));
+    }
+
+    @Test
+    void getApproval_ExistingId_ReturnsApproval() {
+        when(repository.findById(1L)).thenReturn(Optional.of(savedApproval));
+        ApprovalResponse response = service.getApproval(1L);
+        assertNotNull(response);
+        assertEquals(1L, response.getId());
+    }
+
+    @Test
+    void getApproval_NonExistingId_ThrowsException() {
+        when(repository.findById(999L)).thenReturn(Optional.empty());
+        assertThrows(ApprovalProcessingException.class, () -> service.getApproval(999L));
+    }
+
+    @Test
+    void getPendingApprovals_ReturnsPendingList() {
+        AcquisitionApproval pending1 = new AcquisitionApproval();
+        pending1.setId(1L);
+        pending1.setStatus(ApprovalStatus.PENDING);
+        pending1.setMerchantId("MERCHANT001");
+
+        AcquisitionApproval pending2 = new AcquisitionApproval();
+        pending2.setId(2L);
+        pending2.setStatus(ApprovalStatus.PENDING);
+        pending2.setMerchantId("MERCHANT002");
+
+        when(repository.findByStatus(ApprovalStatus.PENDING)).thenReturn(Arrays.asList(pending1, pending2));
+
+        List<ApprovalResponse> responses = service.getPendingApprovals();
+        assertEquals(2, responses.size());
+    }
+
+    @Test
+    void getApprovalsByMerchant_ReturnsMerchantApprovals() {
+        when(repository.findByMerchantId("MERCHANT001")).thenReturn(Arrays.asList(savedApproval));
+
+        List<ApprovalResponse> responses = service.getApprovalsByMerchant("MERCHANT001");
+        assertEquals(1, responses.size());
+        assertEquals("MERCHANT001", responses.get(0).getMerchantId());
+    }
+}
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