diff --git a/src/main/java/com/onixbyte/helix/controller/DepartmentController.java b/src/main/java/com/onixbyte/helix/controller/DepartmentController.java
index 34c5a5e..24117e5 100644
--- a/src/main/java/com/onixbyte/helix/controller/DepartmentController.java
+++ b/src/main/java/com/onixbyte/helix/controller/DepartmentController.java
@@ -2,11 +2,11 @@ package com.onixbyte.helix.controller;
 
 import com.onixbyte.helix.domain.entity.Department;
 import com.onixbyte.helix.domain.common.TreeNode;
+import com.onixbyte.helix.domain.web.request.AddDepartmentRequest;
 import com.onixbyte.helix.service.DepartmentService;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.RequestMapping;
-import org.springframework.web.bind.annotation.RestController;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
 
@@ -36,4 +36,9 @@ public class DepartmentController {
     public List<Department> getDepartments() {
         return departmentService.getDepartments();
     }
+
+    @PostMapping
+    public Department addDepartment(@Validated @RequestBody AddDepartmentRequest request) {
+        return departmentService.addDepartment(request);
+    }
 }
diff --git a/src/main/java/com/onixbyte/helix/controller/ExceptionController.java b/src/main/java/com/onixbyte/helix/controller/ExceptionController.java
index f8a6677..dbec193 100644
--- a/src/main/java/com/onixbyte/helix/controller/ExceptionController.java
+++ b/src/main/java/com/onixbyte/helix/controller/ExceptionController.java
@@ -3,8 +3,10 @@ package com.onixbyte.helix.controller;
 import com.onixbyte.helix.domain.web.response.BizExceptionResponse;
 import com.onixbyte.helix.exception.BizException;
 import jakarta.validation.ConstraintViolationException;
+import org.springframework.context.support.DefaultMessageSourceResolvable;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
@@ -25,22 +27,6 @@ import java.util.stream.Collectors;
 @RestControllerAdvice
 public class ExceptionController {
 
-    /**
-     * Handles business logic exceptions thrown throughout the application.
-     * <p>
-     * This method intercepts {@link BizException} instances and converts them into appropriate HTTP
-     * responses. The HTTP status code is determined by the exception's status property, whilst the
-     * error message is extracted from the exception and included in the response body.
-     * <p>
-     * The response includes a timestamp indicating when the error occurred and the specific error
-     * message describing the business logic violation.
-     *
-     * @param ex the business exception that was thrown
-     * @return a {@link ResponseEntity} containing the error response with appropriate HTTP status
-     * and {@link BizExceptionResponse} body
-     * @see BizException
-     * @see BizExceptionResponse
-     */
     @ExceptionHandler(BizException.class)
     public ResponseEntity<BizExceptionResponse> handleBizException(BizException ex) {
         return ResponseEntity.status(ex.getStatus())
@@ -50,25 +36,6 @@ public class ExceptionController {
                 );
     }
 
-    /**
-     * Handles bean validation constraint violation exceptions.
-     * <p>
-     * This method processes {@link ConstraintViolationException} instances that occur when bean
-     * validation constraints are violated during request processing. It extracts all constraint
-     * violations, formats them into a readable error message, and returns a standardised
-     * error response.
-     * <p>
-     * The error message includes the property path and violation message for each constraint that
-     * was violated, separated by commas for multiple violations. The response is automatically
-     * assigned a {@code 400 Bad Request} status.
-     *
-     * @param ex the constraint violation exception containing validation errors
-     * @return a {@link BizExceptionResponse} containing the formatted validation
-     * error messages and timestamp
-     * @see ConstraintViolationException
-     * @see BizExceptionResponse
-     * @see jakarta.validation.constraints
-     */
     @ExceptionHandler(ConstraintViolationException.class)
     @ResponseStatus(HttpStatus.BAD_REQUEST)
     public BizExceptionResponse handleConstraintViolation(ConstraintViolationException ex) {
@@ -81,4 +48,19 @@ public class ExceptionController {
                 errorMessage
         );
     }
+
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    @ResponseStatus(HttpStatus.BAD_REQUEST)
+    public BizExceptionResponse handleMethodArgumentNotValid(MethodArgumentNotValidException ex) {
+        var errorMessage = ex.getBindingResult()
+                .getFieldErrors()
+                .stream()
+                .map(DefaultMessageSourceResolvable::getDefaultMessage)
+                .collect(Collectors.joining("; "));
+
+        return new BizExceptionResponse(
+                LocalDateTime.now(),
+                errorMessage
+        );
+    }
 }
diff --git a/src/main/java/com/onixbyte/helix/domain/entity/User.java b/src/main/java/com/onixbyte/helix/domain/entity/User.java
index dae750e..3523650 100644
--- a/src/main/java/com/onixbyte/helix/domain/entity/User.java
+++ b/src/main/java/com/onixbyte/helix/domain/entity/User.java
@@ -22,7 +22,7 @@ import java.util.Objects;
  */
 @Entity
 @Table(
-        name = "user",
+    name = "\"user\"",
         uniqueConstraints = {
                 @UniqueConstraint(name = "uidx_users_username", columnNames = {"username"}),
                 @UniqueConstraint(name = "uidx_users_email", columnNames = {"email"}),
diff --git a/src/main/java/com/onixbyte/helix/domain/web/request/AddDepartmentRequest.java b/src/main/java/com/onixbyte/helix/domain/web/request/AddDepartmentRequest.java
new file mode 100644
index 0000000..7b31ee9
--- /dev/null
+++ b/src/main/java/com/onixbyte/helix/domain/web/request/AddDepartmentRequest.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024-2026 OnixByte
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.onixbyte.helix.domain.web.request;
+
+import com.onixbyte.helix.enumeration.Status;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public record AddDepartmentRequest(
+        @NotNull(message = "Name of the department should not be null")
+        @NotBlank(message = "Name of the department should not be null")
+        String name,
+        Long parentId,
+        Integer sort,
+        Status status
+) {
+}
diff --git a/src/main/java/com/onixbyte/helix/manager/DepartmentManager.java b/src/main/java/com/onixbyte/helix/manager/DepartmentManager.java
index 1c88c20..db9524e 100644
--- a/src/main/java/com/onixbyte/helix/manager/DepartmentManager.java
+++ b/src/main/java/com/onixbyte/helix/manager/DepartmentManager.java
@@ -8,6 +8,8 @@ import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.stereotype.Component;
 
+import java.util.Optional;
+
 @Component
 public class DepartmentManager {
 
@@ -27,4 +29,12 @@ public class DepartmentManager {
     public Department selectById(Long id) {
         return departmentRepository.findById(id).orElse(null);
     }
+
+    public Integer getNextSort(Long parentId) {
+        return Optional.ofNullable(departmentRepository.findMaxSort(parentId)).orElse(0) + 1;
+    }
+
+    public Department save(Department department) {
+        return departmentRepository.save(department);
+    }
 }
diff --git a/src/main/java/com/onixbyte/helix/manager/UserManager.java b/src/main/java/com/onixbyte/helix/manager/UserManager.java
index 80dcbc1..4c986b3 100644
--- a/src/main/java/com/onixbyte/helix/manager/UserManager.java
+++ b/src/main/java/com/onixbyte/helix/manager/UserManager.java
@@ -1,3 +1,25 @@
+/*
+ * Copyright (c) 2024-2026 OnixByte
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
 package com.onixbyte.helix.manager;
 
 import com.onixbyte.helix.common.regex.Patterns;
diff --git a/src/main/java/com/onixbyte/helix/repository/DepartmentRepository.java b/src/main/java/com/onixbyte/helix/repository/DepartmentRepository.java
index 70ceeab..79a1849 100644
--- a/src/main/java/com/onixbyte/helix/repository/DepartmentRepository.java
+++ b/src/main/java/com/onixbyte/helix/repository/DepartmentRepository.java
@@ -2,8 +2,17 @@ package com.onixbyte.helix.repository;
 
 import com.onixbyte.helix.domain.entity.Department;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
 
 @Repository
 public interface DepartmentRepository extends JpaRepository<Department, Long> {
+
+    @Query("""
+            select max(d.sort)
+            from Department d
+            where (:parentId is null and d.parentId is null)
+               or d.parentId = :parentId
+            """)
+    Integer findMaxSort(Long parentId);
 }
diff --git a/src/main/java/com/onixbyte/helix/service/DepartmentService.java b/src/main/java/com/onixbyte/helix/service/DepartmentService.java
index 0cae30a..41e5a8c 100644
--- a/src/main/java/com/onixbyte/helix/service/DepartmentService.java
+++ b/src/main/java/com/onixbyte/helix/service/DepartmentService.java
@@ -1,14 +1,19 @@
 package com.onixbyte.helix.service;
 
-import com.onixbyte.helix.domain.entity.Department;
 import com.onixbyte.helix.domain.common.TreeNode;
+import com.onixbyte.helix.domain.entity.Department;
+import com.onixbyte.helix.domain.web.request.AddDepartmentRequest;
+import com.onixbyte.helix.enumeration.Status;
 import com.onixbyte.helix.manager.DepartmentManager;
 import com.onixbyte.helix.utils.TreeUtil;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.Pageable;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
+import java.time.LocalDateTime;
 import java.util.List;
+import java.util.Optional;
 
 @Service
 public class DepartmentService {
@@ -28,4 +33,22 @@ public class DepartmentService {
     public List<Department> getDepartments() {
         return departmentManager.selectAll(Pageable.unpaged()).getContent();
     }
+
+    @Transactional(rollbackFor = Throwable.class)
+    public Department addDepartment(AddDepartmentRequest request) {
+        var createdAt = LocalDateTime.now();
+
+        var parentId = request.parentId();
+        var sort = Optional.ofNullable(request.sort())
+                .orElseGet(() -> departmentManager.getNextSort(parentId));
+
+        return departmentManager.save(Department.builder()
+                .name(request.name())
+                .parentId(parentId)
+                .sort(sort)
+                .status(Optional.ofNullable(request.status()).orElse(Status.ACTIVE))
+                .createdAt(createdAt)
+                .updatedAt(createdAt)
+                .build());
+    }
 }
diff --git a/src/main/resources/db/migrations/V1__init_db.sql b/src/main/resources/db/migrations/V1__init_db.sql
index 5073696..61213ee 100644
--- a/src/main/resources/db/migrations/V1__init_db.sql
+++ b/src/main/resources/db/migrations/V1__init_db.sql
@@ -409,4 +409,21 @@ FROM system_menu;
 INSERT INTO menu (name, parent_id, code, sort, path, is_external_link, is_visible, status,
                   authority_code, icon, created_at, updated_at)
 VALUES ('Helix 官网', null, 'helix-official-site', 100, 'https://helix.onixbyte.com', true, true,
-        'ACTIVE'::STATUS, null, null, NOW(), NOW());
\ No newline at end of file
+        'ACTIVE'::STATUS, null, null, NOW(), NOW());
+
+DO
+$$
+    DECLARE
+        v_user_id BIGINT;
+        v_now     TIMESTAMP;
+    BEGIN
+        SELECT id INTO v_user_id FROM "user" WHERE username = 'helix';
+        v_now := CURRENT_TIMESTAMP;
+
+        RAISE NOTICE 'User ID: %, Timestamp: %', v_user_id, v_now;
+
+        -- Default password is '123456'
+        INSERT INTO "user_credential"
+        VALUES (v_user_id, 'LOCAL'::credential_provider, '$2a$10$1LoatLVvHL3LFK0pnNXcM.eiPK6.UdA9cl9IDwanWHBAAILn1xe0K', v_now, v_now);
+    END;
+$$;
\ No newline at end of file