PURPOSE: To execute quickly an image display, by limiting an initial running time of a belt-like photoreceptor in a cycle for forming and displaying one image, to that which is necessary and sufficient.

CONSTITUTION: An encoder 16 is fitted to a motor 15 for turning an endless belt-like photoreceptor which is driven intermittently, the number of output pulses of the encoder 16 is converted to voltage by an f/v transducer 17, this voltage is compared with a speed commmand generator 19 by a comparator 18, and its compared signal is fed back to the motor 15 through an amplifier 20, by which control voltage of the motor 15 is controlled so that its rotation is kept constant. Also, an output signal of the comparator 18 is inputted to a controller 21 of an exposure write means, and after a turning of the photoreceptor is started, when it reaches a prescribed speed, the exposure write process is started by the controller 21, therefore, an initial running time extending from start of the turning to start of the expousre write can be made shortest at all times.