An image forming apparatus includes: a request signal generating unit that generates a predetermined timing signal and transmits a request signal for a specified number of times for requesting line-by-line image data during a time interval at which the timing signal is generated; and a memory control unit that sequentially saves, in a memory unit, line-by-line image data transmitted in response to the request signal and reads line-by-line image data saved in the memory unit to transmit the line-by-line image data to a drive control unit. Upon receiving a predetermined increase request, the request signal generating unit shifts a generation timing of the timing signal so that, during the time interval, the request signal can be transmitted for an increased number of times than the specified number of times, and gradually shortens the timing signal by a predetermined shortening time period.