diff --git a/XisongSpaceBooking_BackEnd/Models/Entities/AccountEntity.cs b/XisongSpaceBooking_BackEnd/Models/Entities/AccountEntity.cs
new file mode 100644
index 0000000..37eec06
--- /dev/null
+++ b/XisongSpaceBooking_BackEnd/Models/Entities/AccountEntity.cs
@@ -0,0 +1,81 @@
+using XisongSpaceBooking_BackEnd.Models.Entities;
+
+namespace Models.Entities
+{
+    /// <summary>
+    /// 帳號實體類別，對應資料庫 accounts 表格
+    /// </summary>
+    public class AccountEntity : BaseEntity
+    {
+        /// <summary>
+        /// 帳號 ID（主鍵）
+        /// </summary>
+        public int AccountId { get; set; }
+
+        /// <summary>
+        /// 使用者姓名
+        /// </summary>
+        public string Name { get; set; } = string.Empty;
+        
+        /// <summary>
+        /// 帳號名稱（唯一）
+        /// </summary>
+        public string Username { get; set; } = string.Empty;
+        
+        /// <summary>
+        /// 密碼（加密）
+        /// </summary>
+        public string Password { get; set; } = string.Empty;
+        
+        /// <summary>
+        /// 電子郵件（唯一）
+        /// </summary>
+        public string Email { get; set; } = string.Empty;
+
+        /// <summary>
+        /// 處室 ID（外鍵）
+        /// </summary>
+        public int DepartmentId { get; set; }
+        
+        /// <summary>
+        /// 身份 ID（外鍵）
+        /// </summary>
+        public int RoleId { get; set; }
+        
+        /// <summary>
+        /// 帳號狀態
+        /// </summary>
+        public AccountStatus Status { get; set; }
+
+        /// <summary>
+        /// 關聯的處室資訊
+        /// </summary>
+        public DepartmentEntity? Department { get; set; }
+        
+        /// <summary>
+        /// 關聯的身份資訊
+        /// </summary>
+        public RoleEntity? Role { get; set; }
+    }
+
+    /// <summary>
+    /// 帳號狀態列舉
+    /// </summary>
+    public enum AccountStatus
+    {
+        /// <summary>
+        /// 已啟用
+        /// </summary>
+        Enabled,
+        
+        /// <summary>
+        /// 已停用
+        /// </summary>
+        Disabled,
+        
+        /// <summary>
+        /// 未驗證（預設值）
+        /// </summary>
+        Unverified
+    }
+}
\ No newline at end of file
diff --git a/XisongSpaceBooking_BackEnd/Models/Entities/BaseEntity.cs b/XisongSpaceBooking_BackEnd/Models/Entities/BaseEntity.cs
new file mode 100644
index 0000000..dfe9dff
--- /dev/null
+++ b/XisongSpaceBooking_BackEnd/Models/Entities/BaseEntity.cs
@@ -0,0 +1,9 @@
+namespace XisongSpaceBooking_BackEnd.Models.Entities
+{
+    public class BaseEntity
+    {
+        public DateTime CreatedAt { get; set; }
+        public DateTime? UpdatedAt { get; set; }
+        public int? ModifiedBy { get; set; }
+    }
+}
diff --git a/XisongSpaceBooking_BackEnd/Models/Entities/DepartmentEntity.cs b/XisongSpaceBooking_BackEnd/Models/Entities/DepartmentEntity.cs
new file mode 100644
index 0000000..bda1a7c
--- /dev/null
+++ b/XisongSpaceBooking_BackEnd/Models/Entities/DepartmentEntity.cs
@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+
+namespace Models.Entities
+{
+    /// <summary>
+    /// 處室實體類別，對應資料庫 departments 表格
+    /// </summary>
+    public class DepartmentEntity
+    {
+        /// <summary>
+        /// 處室 ID（主鍵）
+        /// </summary>
+        public int DepartmentId { get; set; }
+        
+        /// <summary>
+        /// 處室名稱
+        /// </summary>
+        public string DepartmentName { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/XisongSpaceBooking_BackEnd/Models/Entities/RoleEntity.cs b/XisongSpaceBooking_BackEnd/Models/Entities/RoleEntity.cs
new file mode 100644
index 0000000..ee24e94
--- /dev/null
+++ b/XisongSpaceBooking_BackEnd/Models/Entities/RoleEntity.cs
@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+
+namespace Models.Entities
+{
+    /// <summary>
+    /// 身份實體類別，對應資料庫 roles 表格
+    /// </summary>
+    public class RoleEntity
+    {
+        /// <summary>
+        /// 身份 ID（主鍵）
+        /// </summary>
+        public int RoleId { get; set; }
+        
+        /// <summary>
+        /// 身份名稱
+        /// </summary>
+        public string RoleName { get; set; }
+    }
+}
\ No newline at end of file