A drive system for driving a chuck device includes a controller and a switching valve, which is a 5-port servo valve, switching the state of supply of compressed air to the chuck device based on a valve command signal from the controller. During switching of first and second fingers from a closed position to an open position, when the axial position of a piston reaches a switch point, which is a predetermined distance short of a target position corresponding to a freely selected intermediate position of the first and second fingers, the switching valve is opened at a third opening for a predetermined period and then switched to be opened at a fourth opening so that supply and discharge of compressed air are stopped. As a result, the first and second fingers stop in the intermediate position.