PURPOSE: To obtain a picture with high quality smoothed by taking not only a main scanning direction but also a subscanning direction into account.

CONSTITUTION: A latch circuit 501 latches digital picture data in an image forming timing control block 109, a latch circuit 502 latches delay quantity data, an image forming timing signal generating circuit 503 generates a timing signal for image forming based on delay data and a delay quantity calculation circuit 504 calculates a delay in response to the delay data according to a timing signal generated by the image forming timing signal generating circuit 503 and a delay generating circuit 506 controls a timing when digital picture data latched in the latch circuit 501 are outputted according to the delay set by the delay calculation circuit 504.