diff --git a/backend/pmr_api.py b/backend/pmr_api.py
index b97c738..d9158ab 100644
--- a/backend/pmr_api.py
+++ b/backend/pmr_api.py
@@ -518,3 +518,113 @@ def create_label_image(patient_name, med_name, add_info='', dosage=0, frequency=
     draw_centered("청 춘 약 국", pharmacy_y, info_font)
     
     return image
+
+
+# ─────────────────────────────────────────────────────────────
+# API: 환자 이전 처방 이력
+# ─────────────────────────────────────────────────────────────
+@pmr_bp.route('/api/patient/<cus_code>/history', methods=['GET'])
+def get_patient_history(cus_code):
+    """
+    환자 이전 처방 이력 조회
+    
+    Args:
+        cus_code: 환자 고유코드 (CusCode)
+        
+    Query Params:
+        - limit: 최대 조회 건수 (기본 10, 최대 50)
+        - exclude: 제외할 처방번호 (현재 처방)
+    """
+    try:
+        limit = min(int(request.args.get('limit', 10)), 50)
+        exclude_serial = request.args.get('exclude', '')
+        
+        conn = get_mssql_connection('PM_PRES')
+        cursor = conn.cursor()
+        
+        # 이전 처방 목록 조회
+        query = """
+            SELECT TOP (?)
+                m.PreSerial,
+                m.PassDay,
+                m.PresTime,
+                m.Paname,
+                m.InsName,
+                m.Drname,
+                m.PRICE_P,
+                (SELECT COUNT(*) FROM PS_sub_pharm WHERE PreSerial = m.PreSerial) as drug_count
+            FROM PS_MAIN m
+            WHERE m.CusCode = ?
+        """
+        params = [limit, cus_code]
+        
+        if exclude_serial:
+            query += " AND m.PreSerial != ?"
+            params.append(exclude_serial)
+        
+        query += " ORDER BY m.PassDay DESC, m.PresTime DESC"
+        
+        cursor.execute(query, params)
+        
+        history = []
+        for row in cursor.fetchall():
+            pre_serial = row.PreSerial
+            
+            # 해당 처방의 약품 목록 조회
+            cursor.execute("""
+                SELECT 
+                    s.DrugCode,
+                    s.Days,
+                    s.QUAN,
+                    s.QUAN_TIME,
+                    g.GoodsName,
+                    m.PRINT_TYPE
+                FROM PS_sub_pharm s
+                LEFT JOIN PM_DRUG.dbo.CD_GOODS g ON s.DrugCode = g.DrugCode
+                LEFT JOIN PM_DRUG.dbo.CD_MC m ON s.DrugCode = m.DRUGCODE
+                WHERE s.PreSerial = ?
+                ORDER BY s.SUB_SERIAL
+            """, (pre_serial,))
+            
+            medications = []
+            for med_row in cursor.fetchall():
+                medications.append({
+                    'medication_code': med_row.DrugCode or '',
+                    'med_name': med_row.GoodsName or med_row.DrugCode or '',
+                    'add_info': med_row.PRINT_TYPE or '',
+                    'dosage': float(med_row.QUAN) if med_row.QUAN else 0,
+                    'frequency': med_row.QUAN_TIME or 0,
+                    'duration': med_row.Days or 0
+                })
+            
+            # 날짜 포맷
+            pass_day = row.PassDay
+            if pass_day and len(pass_day) == 8:
+                date_formatted = f"{pass_day[:4]}-{pass_day[4:6]}-{pass_day[6:8]}"
+            else:
+                date_formatted = pass_day or ''
+            
+            history.append({
+                'prescription_id': pre_serial,
+                'date': date_formatted,
+                'time': row.PresTime or '',
+                'patient_name': row.Paname or '',
+                'hospital': row.InsName or '',
+                'doctor': row.Drname or '',
+                'copayment': int(row.PRICE_P or 0),
+                'medication_count': row.drug_count or 0,
+                'medications': medications
+            })
+        
+        conn.close()
+        
+        return jsonify({
+            'success': True,
+            'cus_code': cus_code,
+            'count': len(history),
+            'history': history
+        })
+        
+    except Exception as e:
+        logging.error(f"환자 이전 처방 조회 오류: {e}")
+        return jsonify({'success': False, 'error': str(e)}), 500
diff --git a/backend/templates/pmr.html b/backend/templates/pmr.html
index 8c39e33..a1c7be2 100644
--- a/backend/templates/pmr.html
+++ b/backend/templates/pmr.html
@@ -242,6 +242,75 @@
             animation: spin 1s linear infinite;
         }
         @keyframes spin { to { transform: rotate(360deg); } }
+        
+        /* 이전 처방 비교 영역 */
+        .history-section {
+            border-top: 3px solid #e2e8f0;
+            background: #fafafa;
+        }
+        .history-header {
+            background: linear-gradient(135deg, #64748b, #94a3b8);
+            color: #fff;
+            padding: 12px 20px;
+            display: flex;
+            justify-content: space-between;
+            align-items: center;
+        }
+        .history-header .title { font-weight: 600; }
+        .history-nav {
+            display: flex;
+            align-items: center;
+            gap: 10px;
+        }
+        .history-nav button {
+            background: rgba(255,255,255,0.2);
+            border: none;
+            color: #fff;
+            width: 32px;
+            height: 32px;
+            border-radius: 50%;
+            font-size: 1.1rem;
+            cursor: pointer;
+            transition: all 0.2s;
+        }
+        .history-nav button:hover:not(:disabled) { background: rgba(255,255,255,0.4); }
+        .history-nav button:disabled { opacity: 0.4; cursor: not-allowed; }
+        .history-nav .index { font-size: 0.9rem; }
+        .history-info {
+            padding: 10px 20px;
+            background: #f1f5f9;
+            font-size: 0.85rem;
+            color: #64748b;
+            display: flex;
+            gap: 15px;
+        }
+        .history-meds {
+            max-height: 200px;
+            overflow-y: auto;
+            padding: 10px 20px;
+        }
+        .history-meds table {
+            width: 100%;
+            border-collapse: collapse;
+            font-size: 0.85rem;
+        }
+        .history-meds th {
+            background: #e2e8f0;
+            padding: 8px 10px;
+            text-align: left;
+            font-weight: 600;
+            color: #475569;
+        }
+        .history-meds td {
+            padding: 8px 10px;
+            border-bottom: 1px solid #e2e8f0;
+        }
+        .history-meds .med-name { font-weight: 500; }
+        .history-empty {
+            padding: 30px;
+            text-align: center;
+            color: #94a3b8;
+        }
     </style>
 </head>
 <body>
@@ -310,11 +379,30 @@
                     </div>
                 </div>
             </div>
+            
+            <!-- 이전 처방 비교 -->
+            <div class="history-section" id="historySection" style="display:none;">
+                <div class="history-header">
+                    <span class="title">📜 이전 처방</span>
+                    <div class="history-nav">
+                        <button onclick="prevHistory()" id="historyPrev" disabled>‹</button>
+                        <span class="index" id="historyIndex">-</span>
+                        <button onclick="nextHistory()" id="historyNext" disabled>›</button>
+                    </div>
+                </div>
+                <div class="history-info" id="historyInfo"></div>
+                <div class="history-meds" id="historyMeds">
+                    <div class="history-empty">이전 처방 없음</div>
+                </div>
+            </div>
         </div>
     </div>
 
     <script>
         let currentPrescriptionId = null;
+        let currentPatientCode = null;
+        let historyData = [];
+        let historyIndex = 0;
         
         // HTML 이스케이프
         function escapeHtml(text) {
@@ -458,16 +546,117 @@
                     }
                     
                     document.getElementById('actionBar').style.display = 'flex';
+                    
+                    // 이전 처방 로드
+                    currentPatientCode = data.patient.code;
+                    if (currentPatientCode) {
+                        loadPatientHistory(currentPatientCode, prescriptionId);
+                    }
                 }
             } catch (err) {
                 medList.innerHTML = `<div class="empty-state"><div class="text">오류: ${err.message}</div></div>`;
             }
         }
         
+        // 환자 이전 처방 로드
+        async function loadPatientHistory(cusCode, excludeSerial) {
+            const section = document.getElementById('historySection');
+            const medsDiv = document.getElementById('historyMeds');
+            
+            try {
+                const res = await fetch(`/pmr/api/patient/${cusCode}/history?limit=10&exclude=${excludeSerial}`);
+                const data = await res.json();
+                
+                if (data.success && data.history.length > 0) {
+                    historyData = data.history;
+                    historyIndex = 0;
+                    section.style.display = 'block';
+                    renderHistory();
+                } else {
+                    section.style.display = 'none';
+                    historyData = [];
+                }
+            } catch (err) {
+                console.error('History error:', err);
+                section.style.display = 'none';
+            }
+        }
+        
+        // 이전 처방 렌더링
+        function renderHistory() {
+            if (historyData.length === 0) return;
+            
+            const h = historyData[historyIndex];
+            
+            // 인덱스 표시
+            document.getElementById('historyIndex').textContent = 
+                `${historyIndex + 1} / ${historyData.length}`;
+            
+            // 네비게이션 버튼
+            document.getElementById('historyPrev').disabled = historyIndex <= 0;
+            document.getElementById('historyNext').disabled = historyIndex >= historyData.length - 1;
+            
+            // 정보
+            document.getElementById('historyInfo').innerHTML = `
+                <span>📅 ${h.date}</span>
+                <span>🏥 ${h.hospital || '-'}</span>
+                <span>👨‍⚕️ ${h.doctor || '-'}</span>
+                <span>💊 ${h.medication_count}종</span>
+                <span>💰 ${(h.copayment || 0).toLocaleString()}원</span>
+            `;
+            
+            // 약품 테이블
+            if (h.medications && h.medications.length > 0) {
+                document.getElementById('historyMeds').innerHTML = `
+                    <table>
+                        <thead>
+                            <tr>
+                                <th>약품명</th>
+                                <th>용량</th>
+                                <th>횟수</th>
+                                <th>일수</th>
+                            </tr>
+                        </thead>
+                        <tbody>
+                            ${h.medications.map(m => `
+                                <tr>
+                                    <td>
+                                        <div class="med-name">${m.med_name || m.medication_code}</div>
+                                        ${m.add_info ? `<div style="font-size:0.7rem;color:#94a3b8;">${escapeHtml(m.add_info)}</div>` : ''}
+                                    </td>
+                                    <td>${m.dosage || '-'}</td>
+                                    <td>${m.frequency || '-'}회</td>
+                                    <td>${m.duration || '-'}일</td>
+                                </tr>
+                            `).join('')}
+                        </tbody>
+                    </table>
+                `;
+            } else {
+                document.getElementById('historyMeds').innerHTML = '<div class="history-empty">약품 정보 없음</div>';
+            }
+        }
+        
+        // 이전 처방 네비게이션
+        function prevHistory() {
+            if (historyIndex > 0) {
+                historyIndex--;
+                renderHistory();
+            }
+        }
+        
+        function nextHistory() {
+            if (historyIndex < historyData.length - 1) {
+                historyIndex++;
+                renderHistory();
+            }
+        }
+        
         // 상세 초기화
         function clearDetail() {
             document.getElementById('detailHeader').style.display = 'none';
             document.getElementById('actionBar').style.display = 'none';
+            document.getElementById('historySection').style.display = 'none';
             document.getElementById('medicationList').innerHTML = `
                 <div class="empty-state">
                     <div class="icon">👈</div>
@@ -475,6 +664,9 @@
                 </div>
             `;
             currentPrescriptionId = null;
+            currentPatientCode = null;
+            historyData = [];
+            historyIndex = 0;
         }
         
         // 전체 선택 토글