diff --git a/src/main/java/com/acquirex/service/ApprovalService.java b/src/main/java/com/acquirex/service/ApprovalService.java
new file mode 100644
index 0000000..3dffa02
--- /dev/null
+++ b/src/main/java/com/acquirex/service/ApprovalService.java
@@ -0,0 +1,110 @@
+package com.acquirex.service;
+
+import com.acquirex.domain.AcquisitionCard;
+import com.acquirex.domain.ApprovalRequest;
+import com.acquirex.dto.ApprovalRequestDto;
+import com.acquirex.dto.ApprovalResponseDto;
+import com.acquirex.repository.AcquisitionCardRepository;
+import com.acquirex.repository.ApprovalRequestRepository;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.LocalDateTime;
+import java.util.UUID;
+
+@Service
+public class ApprovalService {
+
+    private final ApprovalRequestRepository approvalRequestRepository;
+    private final AcquisitionCardRepository acquisitionCardRepository;
+
+    public ApprovalService(ApprovalRequestRepository approvalRequestRepository,
+                          AcquisitionCardRepository acquisitionCardRepository) {
+        this.approvalRequestRepository = approvalRequestRepository;
+        this.acquisitionCardRepository = acquisitionCardRepository;
+    }
+
+    @Transactional
+    public ApprovalResponseDto requestApproval(ApprovalRequestDto dto) {
+        String transactionId = generateTransactionId();
+
+        AcquisitionCard card = acquisitionCardRepository
+                .findByCardNumberAndCardCompanyCode(dto.getCardNumber(), dto.getCardCompanyCode())
+                .orElseGet(() -> createNewCard(dto));
+
+        ApprovalRequest request = new ApprovalRequest();
+        request.setCardId(card.getId());
+        request.setTransactionId(transactionId);
+        request.setAmount(dto.getAmount());
+        request.setVat(dto.getVat());
+        request.setApprovalStatus(ApprovalRequest.ApprovalStatus.REQUESTED);
+
+        ApprovalRequest saved = approvalRequestRepository.save(request);
+        return buildApprovalResponse(saved, "매입 승인 요청이 완료되었습니다");
+    }
+
+    @Transactional
+    public ApprovalResponseDto approveRequest(Long requestId) {
+        ApprovalRequest request = approvalRequestRepository.findById(requestId)
+                .orElseThrow(() -> new IllegalArgumentException("승인 요청을 찾을 수 없습니다: " + requestId));
+
+        if (request.getApprovalStatus() != ApprovalRequest.ApprovalStatus.REQUESTED) {
+            throw new IllegalStateException("이미 처리된 요청입니다");
+        }
+
+        request.setApprovalNumber(generateApprovalNumber());
+        request.setApprovalStatus(ApprovalRequest.ApprovalStatus.APPROVED);
+        request.setApprovedAt(LocalDateTime.now());
+
+        ApprovalRequest saved = approvalRequestRepository.save(request);
+        return buildApprovalResponse(saved, "매입 승인이 완료되었습니다");
+    }
+
+    @Transactional
+    public ApprovalResponseDto rejectRequest(Long requestId, String reason) {
+        ApprovalRequest request = approvalRequestRepository.findById(requestId)
+                .orElseThrow(() -> new IllegalArgumentException("승인 요청을 찾을 수 없습니다: " + requestId));
+
+        if (request.getApprovalStatus() != ApprovalRequest.ApprovalStatus.REQUESTED) {
+            throw new IllegalStateException("이미 처리된 요청입니다");
+        }
+
+        request.setApprovalStatus(ApprovalRequest.ApprovalStatus.REJECTED);
+        request.setRejectionReason(reason);
+
+        ApprovalRequest saved = approvalRequestRepository.save(request);
+        return buildApprovalResponse(saved, "매입 승인이 거절되었습니다");
+    }
+
+    @Transactional(readOnly = true)
+    public ApprovalResponseDto getApprovalStatus(Long requestId) {
+        ApprovalRequest request = approvalRequestRepository.findById(requestId)
+                .orElseThrow(() -> new IllegalArgumentException("승인 요청을 찾을 수 없습니다: " + requestId));
+        return buildApprovalResponse(request, "조회가 완료되었습니다");
+    }
+
+    private AcquisitionCard createNewCard(ApprovalRequestDto dto) {
+        AcquisitionCard card = new AcquisitionCard();
+        card.setCardNumber(dto.getCardNumber());
+        card.setCardCompanyCode(dto.getCardCompanyCode());
+        card.setMerchantNumber(dto.getMerchantNumber());
+        card.setStatus(AcquisitionCard.CardStatus.PENDING);
+        return acquisitionCardRepository.save(card);
+    }
+
+    private String generateTransactionId() {
+        return "TX" + System.currentTimeMillis() + UUID.randomUUID().toString().substring(0, 8).toUpperCase();
+    }
+
+    private String generateApprovalNumber() {
+        return "AP" + System.currentTimeMillis();
+    }
+
+    private ApprovalResponseDto buildApprovalResponse(ApprovalRequest request, String message) {
+        return new ApprovalResponseDto(
+                request.getId(), request.getTransactionId(), request.getApprovalNumber(),
+                request.getApprovalStatus().name(), request.getAmount(), request.getVat(),
+                request.getApprovedAt(), message
+        );
+    }
+}
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