diff --git a/apps/pos_device/exceptions.py b/apps/pos_device/exceptions.py
index f5f8d10..d4986f9 100644
--- a/apps/pos_device/exceptions.py
+++ b/apps/pos_device/exceptions.py
@@ -2,6 +2,23 @@ from rest_framework import status
 from rest_framework.exceptions import APIException
 
 
+class DeviceException(APIException):
+    status_code = status.HTTP_400_BAD_REQUEST
+    default_detail = "خطا در اطلاعات پلاک"  # noqa
+    default_code = 'error'
+
+    def __init__(self, message=None, status_code=None, code=None):
+        if status_code is not None:
+            self.status_code = status_code
+
+        detail = {
+            "message": message,
+            "status_code": status_code
+        }
+
+        super().__init__(detail)
+
+
 class DeviceAlreadyAssigned(APIException):
     status_code = status.HTTP_403_FORBIDDEN
     default_detail = "این دستگاه قبلا به این کلاینت تخصیص داده شده است"  # noqa
diff --git a/apps/pos_device/migrations/0081_alter_device_serial.py b/apps/pos_device/migrations/0081_alter_device_serial.py
new file mode 100644
index 0000000..313de18
--- /dev/null
+++ b/apps/pos_device/migrations/0081_alter_device_serial.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.0 on 2026-01-26 06:47
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pos_device', '0080_bankaccountdevicelink'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='device',
+            name='serial',
+            field=models.TextField(null=True),
+        ),
+    ]
diff --git a/apps/pos_device/models.py b/apps/pos_device/models.py
index 771787b..38f83cb 100644
--- a/apps/pos_device/models.py
+++ b/apps/pos_device/models.py
@@ -36,7 +36,7 @@ class Device(BaseModel):
     acceptor = models.CharField(max_length=50, null=True)
     terminal = models.CharField(max_length=50, null=True)
     mac = models.CharField(max_length=50, null=True)
-    serial = models.TextField(null=True, unique=True)
+    serial = models.TextField(null=True)
     password = models.CharField(max_length=25, null=True)
     multi_device = models.BooleanField(default=False)
     server_in = models.BooleanField(default=False)
diff --git a/apps/pos_device/web/api/v1/serilaizers/device.py b/apps/pos_device/web/api/v1/serilaizers/device.py
index 929384d..37c97bd 100644
--- a/apps/pos_device/web/api/v1/serilaizers/device.py
+++ b/apps/pos_device/web/api/v1/serilaizers/device.py
@@ -3,6 +3,7 @@ from rest_framework.serializers import ModelSerializer
 from apps.authentication.api.v1.serializers.serializer import BankAccountSerializer
 from apps.pos_device import exceptions as pos_exceptions
 from apps.pos_device import models as pos_models
+from apps.pos_device.exceptions import DeviceException
 from apps.pos_device.web.api.v1.serilaizers import client as client_serializer
 from apps.product.web.api.v1.serializers.quota_distribution_serializers import QuotaDistributionSerializer
 
@@ -18,6 +19,19 @@ class DeviceSerializer(ModelSerializer):
         model = pos_models.Device
         fields = '__all__'
 
+    def validate(self, attrs):
+        serial = attrs['serial']
+
+        if not self.instance:
+            if self.Meta.model.objects.filter(serial=serial).exists():
+                raise DeviceException("دستگاه یا این شماره سریال از قبل ثبت شده است.", status_code=403)  # noqa
+
+        if self.instance:
+            if serial != self.instance.serial and self.Meta.model.objects.filter(serial=serial).exists():
+                raise DeviceException("دستگاهی با این شماره سریال وجود دارد.", status_code=403)  # noqa
+
+        return attrs
+
     def to_representation(self, instance):
         """ custom output of serializer """
         representation = super().to_representation(instance)