diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index d24d6e4e4b3..bc415334515 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -953,12 +953,6 @@ class Task(models.Model):
             else:
                 task.stage_id = False
 
-    @api.constrains('parent_id', 'child_ids')
-    def _check_subtask_level(self):
-        for task in self:
-            if task.parent_id and task.child_ids:
-                raise ValidationError(_('Task %s cannot have several subtask levels.', task.name))
-
     @api.returns('self', lambda value: value.id)
     def copy(self, default=None):
         if default is None: