PURPOSE: To eliminate the need for exchanging of f-θ lenses, increase versatility and electrically achieve the function similar to that of the f-θ lens with an inexpensive constitution by using a counter, memory, D/A converter and voltage control oscillator in place of conventional f-θ lenses.

CONSTITUTION: In the scan control system for making distortion-free electrostatic latent images of high accuracy on a photosensitive drum by laser light, the laser light from a laser device 21 is radiated to the mirror surface of a polygonal mirror 23 via modulator 22 and scans a photosensitive drum 25 from the left to the right by being rotated about its central axis by a motor 24. A photo detector 26 is provided to the left end of the drum 25 and a pulse is outputted at the scan start. This pulse is passed through an amplifier 11 to clear a counter 12, causing the pulses from a timing generator 16 to be counted. The output of the counter 12 is let to the address line of a memory 13, from which the contents of the address corresponding to the address information is outputted. This output is analogized in a D/A converter 14 and is then led to a voltage control oscillator 15, whose output is inputted as a modulating data to the modulator 22 via shift register 18.