In a copying apparatus having an endless photosensitive medium, a number of copy process devices for forming an electrostatic latent image on the photosensitive medium, for developing the latent image, for transferring the developed image and for cleaning the photosensitive medium, there is provided circuitry for controlling the operation of at least one of the copy process devices in accordance with the generation of a predetermined number of clock signals. The control circuitry acts to start the initiation of the copy process after counting a predetermined number of signals and to stop the rotation of the medium at a different rotational position from the start position. The apparatus also includes a jam detecting device and reciprocating member for the formation of the latent image, the position of which is detected for utilization in the control circuitry.