Abstract: An operating device for inputting the coordinate positions of a controlled object that moves across a screen. The present invention is directed to obviating the problems of the prior art involving the bad operability of a knob which requires rotation through a large angle to move the controlled object across the screen, and the short life-span of the knob due to frequent use. In order to overcome these problems, the rotational number of a main shaft is increased by a rotational number increasing mechanism and the rotational number of the output shaft of the rotational number increasing mechanism is optically or magnetically detected. The present invention is therefore suitable for use as an operating device for a TV game machine.