In order to possibly suppress noise components contained in a signal value of a detection signal for use in controlling a rate of rotations or speed, an driving controller receives a detection signal in accordance with a rate of rotations or speed and acquires a signal value of the detection signal every predetermined sampling time, and controls an actuator at control timings with predetermined intervals using the signal value, so that the rate of rotations or speed is controlled at each of the control timings in accordance with variation aspects of a plurality of signal values acquired before the outstanding control timing.