A positioning system using a robot, capable of eliminating an error factor of the robot such as thermal expansion or backlash can be eliminated, and carrying out positioning of the robot with accuracy higher than inherent positioning accuracy of the robot. The positioning system has a robot with a movable arm, visual feature portions provided to a robot hand, and vision sensors positioned at a fixed position outside the robot and configured to capture the feature portions. The hand is configured to grip an object on which the feature portions are formed, and the vision sensors are positioned and configured to capture the respective feature portions.