diff --git a/src/main/java/com/acquirex/approval/CardAcquisitionService.java b/src/main/java/com/acquirex/approval/CardAcquisitionService.java
new file mode 100644
index 0000000..fac8b83
--- /dev/null
+++ b/src/main/java/com/acquirex/approval/CardAcquisitionService.java
@@ -0,0 +1,86 @@
+package com.acquirex.approval;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+import org.springframework.transaction.annotation.Transactional;
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * 카드 매입 서비스 + 리포지토리.
+ * Spring Boot 3 전환: jakarta.transaction.Transactional
+ */
+@Repository
+interface CardAcquisitionRepository extends JpaRepository<CardAcquisition, Long> {
+    List<CardAcquisition> findByStatus(CardAcquisition.ApprovalStatus status);
+    List<CardAcquisition> findByMerchantId(String merchantId);
+}
+
+@Service
+@Transactional
+public class CardAcquisitionService {
+
+    private final CardAcquisitionRepository repository;
+
+    public CardAcquisitionService(CardAcquisitionRepository repository) {
+        this.repository = repository;
+    }
+
+    public CardAcquisition createAcquisition(String cardNumber, String merchantId, BigDecimal amount) {
+        validateAmount(amount);
+        CardAcquisition acquisition = new CardAcquisition(cardNumber, merchantId, amount);
+        return repository.save(acquisition);
+    }
+
+    @Transactional(readOnly = true)
+    public Optional<CardAcquisition> findById(Long id) {
+        return repository.findById(id);
+    }
+
+    @Transactional(readOnly = true)
+    public List<CardAcquisition> findAll() {
+        return repository.findAll();
+    }
+
+    @Transactional(readOnly = true)
+    public List<CardAcquisition> findByStatus(CardAcquisition.ApprovalStatus status) {
+        return repository.findByStatus(status);
+    }
+
+    public CardAcquisition approve(Long id, String approver) {
+        CardAcquisition acquisition = repository.findById(id)
+                .orElseThrow(() -> new IllegalArgumentException("매입 요청을 찾을 수 없습니다: " + id));
+        if (acquisition.getStatus() != CardAcquisition.ApprovalStatus.PENDING) {
+            throw new IllegalStateException("대기 상태의 요청만 승인할 수 있습니다.");
+        }
+        acquisition.approve(approver);
+        return repository.save(acquisition);
+    }
+
+    public CardAcquisition reject(Long id, String reason) {
+        CardAcquisition acquisition = repository.findById(id)
+                .orElseThrow(() -> new IllegalArgumentException("매입 요청을 찾을 수 없습니다: " + id));
+        if (acquisition.getStatus() != CardAcquisition.ApprovalStatus.PENDING) {
+            throw new IllegalStateException("대기 상태의 요청만 거절할 수 있습니다.");
+        }
+        acquisition.reject(reason);
+        return repository.save(acquisition);
+    }
+
+    public CardAcquisition cancel(Long id) {
+        CardAcquisition acquisition = repository.findById(id)
+                .orElseThrow(() -> new IllegalArgumentException("매입 요청을 찾을 수 없습니다: " + id));
+        if (acquisition.getStatus() == CardAcquisition.ApprovalStatus.APPROVED) {
+            throw new IllegalStateException("이미 승인된 요청은 취소할 수 없습니다.");
+        }
+        acquisition.cancel();
+        return repository.save(acquisition);
+    }
+
+    private void validateAmount(BigDecimal amount) {
+        if (amount == null || amount.compareTo(BigDecimal.ZERO) <= 0) {
+            throw new IllegalArgumentException("매입 금액은 0보다 커야 합니다.");
+        }
+    }
+}