diff --git a/README.md b/README.md
index 22bf17d..b01d01a 100644
--- a/README.md
+++ b/README.md
@@ -90,7 +90,7 @@
 
 | 機能 | ファイル | 状態 |
 |------|---------|----|
-| **見積入力** | `lib/screens/estimate_screen.dart` | ✅ 完了（エラーハンドリング追加）<br>- 得意先選択・商品追加<br>- DatabaseHelper を介した保存<br>- エラーハンドリング完全化<br>📝 次のステップ：PDF 帳票出力テンプレート実装
+| **見積入力** | `lib/screens/estimate_screen.dart` | ✅ 完了（エラーハンドリング追加）<br>- 得意先選択・商品追加<br>- DatabaseHelper を介した保存<br>- エラーハンドリング完全化<br>📝 次のステップ：売上入力画面実装
 | DB CRUD API | `lib/services/database_helper.dart` | ✅ Estimate テーブル対応<br>・insertEstimate<br>・getEstimates<br>・estimate CRUD |
 | Estimate モデル | `lib/models/estimate.dart` | ✅ LineItem ネスト構造<br>・toMap/fromMap 実装 |
 
diff --git a/lib/models/sale.dart b/lib/models/sale.dart
new file mode 100644
index 0000000..82ec412
--- /dev/null
+++ b/lib/models/sale.dart
@@ -0,0 +1,73 @@
+// Version: 1.1 (売上モデル実装)
+import 'dart:convert';
+
+class Sale {
+  int? id;
+  String? saleNo;
+  String customerName;
+  DateTime date;
+  double totalAmount;
+  double taxRate;
+  Map<String, dynamic>? items; // LineItem ネスト構造
+  DateTime createdAt;
+  DateTime updatedAt;
+
+  Sale({
+    this.id,
+    this.saleNo,
+    required this.customerName,
+    required this.date,
+    required this.totalAmount,
+    this.taxRate = 10,
+    this.items,
+    DateTime? createdAt,
+    DateTime? updatedAt,
+  })  : createdAt = createdAt ?? DateTime.now(),
+        updatedAt = updatedAt ?? DateTime.now();
+
+  Map<String, dynamic> toMap() {
+    return {
+      'id': id,
+      'sale_no': saleNo,
+      'customer_name': customerName,
+      'date': date.toIso8601String(),
+      'total_amount': totalAmount,
+      'tax_rate': taxRate,
+      'items': items,
+      'created_at': createdAt.toIso8601String(),
+      'updated_at': updatedAt.toIso8601String(),
+    };
+  }
+
+  factory Sale.fromMap(Map<String, dynamic> map) {
+    return Sale(
+      id: map['id'] as int?,
+      saleNo: map['sale_no'] as String?,
+      customerName: map['customer_name'] as String,
+      date: DateTime.parse(map['date'] as String),
+      totalAmount: (map['total_amount'] as num).toDouble(),
+      taxRate: map['tax_rate'] as double? ?? 10,
+      items: map['items'] as Map<String, dynamic>? ,
+      createdAt: map['created_at'] != null ? DateTime.parse(map['created_at']) : DateTime.now(),
+      updatedAt: map['updated_at'] != null ? DateTime.parse(map['updated_at']) : DateTime.now(),
+    );
+  }
+
+  String toJson() => json.encode(toMap());
+
+  factory Sale.fromJson(String source) => Sale.fromMap(json.decode(source) as Map<String, dynamic>);
+
+  @override
+  String toString() {
+    return 'Sale(id: $id, saleNo: $saleNo, customerName: $customerName, date: $date, totalAmount: $totalAmount, taxRate: $taxRate, items: $items)';
+  }
+
+  @override
+  bool operator ==(covariant Sale other) {
+    if (identical(this, other)) return true;
+    return other.id == id && other.saleNo == saleNo;
+  }
+
+  @override
+  int get hashCode => id ^ saleNo;
+}
\ No newline at end of file
diff --git a/lib/services/database_helper.dart b/lib/services/database_helper.dart
index cb1c44b..5b3f42f 100644
--- a/lib/services/database_helper.dart
+++ b/lib/services/database_helper.dart
@@ -108,6 +108,22 @@ class DatabaseHelper {
       )
     ''');
 
+    // sales テーブル（売用书）
+    await db.execute('''
+      CREATE TABLE sales (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        sale_no TEXT NOT NULL UNIQUE,
+        customer_id INTEGER,
+        customer_name TEXT NOT NULL,
+        date TEXT NOT NULL,
+        total_amount REAL NOT NULL,
+        tax_rate REAL DEFAULT 10,
+        items_json TEXT NOT NULL,
+        created_at TEXT NOT NULL,
+        updated_at TEXT NOT NULL
+      )
+    ''');
+
     // customer_snapshots テーブル（イベントソーシング用）
     await db.execute('''
       CREATE TABLE customer_snapshots (