An image acquisition unit acquires an image including an object, and a controller starts a visual servo using the acquired image, on the basis of at least one of an error in calibration, an error in installation of a robot, an error resulting from the rigidity of the robot, an error of a position where the robot has gripped the object, an error regarding imaging, and an error regarding a work environment. Additionally, the controller starts the visual servo when the distance between one point of a working unit of the robot and the object is equal to or greater than 2 mm.