diff --git a/mia_core/models.py b/mia_core/models.py
new file mode 100644
index 0000000..886b028
--- /dev/null
+++ b/mia_core/models.py
@@ -0,0 +1,56 @@
+# The core application of the Mia project.
+#   by imacat <imacat@mail.imacat.idv.tw>, 2020/6/29
+
+#  Copyright (c) 2020 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+"""The data models of the Mia core application.
+
+"""
+from django.conf import settings
+from django.db import models
+
+from mia_core.utils import new_pk
+
+
+class BaseModel(models.Model):
+    """The common abstract base model that has id, created_at, created_by,
+    updated_at, and updated_by."""
+    id = models.PositiveIntegerField(primary_key=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    created_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL, on_delete=models.PROTECT,
+        related_name="created_%(app_label)s_%(class)s")
+    updated_at = models.DateTimeField(auto_now=True)
+    updated_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL, on_delete=models.PROTECT,
+        related_name="updated_%(app_label)s_%(class)s")
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.current_user = None
+
+    def save(self, force_insert=False, force_update=False, using=None,
+             update_fields=None):
+        if self.pk is None:
+            self.pk = new_pk(self.__class__)
+            if self.current_user is not None:
+                self.created_by = self.current_user
+        if self.current_user is not None:
+            self.updated_by = self.current_user
+        super().save(force_insert=force_insert, force_update=force_update,
+                     using=using, update_fields=update_fields)
+
+    class Meta:
+        abstract = True