下記の通りお返事きましたので、実データでテストしてください。

backend/apps/fields/urls.py

@@ -9,4 +9,5 @@ urlpatterns = [
     path('', include(router.urls)),
     path('import/kyosai/', views.import_kyosai_master, name='import_kyosai'),
     path('import/yoshida/', views.import_yoshida_fields, name='import_yoshida'),
+    path('import/chusankan/', views.import_chusankan_master, name='import_chusankan'),
 ]

backend/apps/fields/views.py

@@ -112,18 +112,13 @@ def import_yoshida_fields(request):
             else:
                 updated_count += 1
 
-            if raw_kyosai_k:
+            if raw_kyosai_k and raw_kyosai_s:
                 try:
-                    kyosai_record = OfficialKyosaiField.objects.get(k_num=raw_kyosai_k)
+                    kyosai_record = OfficialKyosaiField.objects.get(k_num=raw_kyosai_k, s_num=raw_kyosai_s)
                     field.kyosai_fields.add(kyosai_record)
                 except OfficialKyosaiField.DoesNotExist:
                     pass
-
-            if raw_kyosai_s:
-                try:
-                    kyosai_record = OfficialKyosaiField.objects.get(s_num=raw_kyosai_s)
-                    field.kyosai_fields.add(kyosai_record)
-                except OfficialKyosaiField.DoesNotExist:
+                except OfficialKyosaiField.MultipleObjectsReturned:
                     pass
 
             if raw_chusankan:
@@ -142,3 +137,53 @@ def import_yoshida_fields(request):
 
     except Exception as e:
         return JsonResponse({'error': str(e)}, status=500)
+
+
+@csrf_exempt
+@require_http_methods(["POST"])
+def import_chusankan_master(request):
+    if 'file' not in request.FILES:
+        return JsonResponse({'error': 'No file uploaded'}, status=400)
+
+    ods_file = request.FILES['file']
+
+    try:
+        df = pd.read_excel(ods_file, engine='odf')
+        df.columns = df.columns.str.strip()
+        
+        created_count = 0
+        updated_count = 0
+
+        for _, row in df.iterrows():
+            c_id = str(row.get('ID', '')).strip() if pd.notna(row.get('ID')) else ''
+            
+            if not c_id:
+                continue
+
+            defaults = {
+                'oaza': str(row.get('大字', '')).strip() if pd.notna(row.get('大字')) else '',
+                'aza': str(row.get('字', '')).strip() if pd.notna(row.get('字')) else '',
+                'chiban': str(row.get('地番', '')).strip() if pd.notna(row.get('地番')) else '',
+                'area': float(row.get('農地面積', 0)) if pd.notna(row.get('農地面積')) else 0,
+                'payment_amount': int(row.get('交付金額', 0)) if pd.notna(row.get('交付金額')) else None,
+            }
+
+            obj, created = OfficialChusankanField.objects.update_or_create(
+                c_id=c_id,
+                defaults=defaults
+            )
+
+            if created:
+                created_count += 1
+            else:
+                updated_count += 1
+
+        return JsonResponse({
+            'success': True,
+            'created': created_count,
+            'updated': updated_count,
+            'message': f'中山間マスタ: {created_count}件作成, {updated_count}件更新'
+        })
+
+    except Exception as e:
+        return JsonResponse({'error': str(e)}, status=500)