An image rendering apparatus includes a light source unit, an optical scanner, a scanner control unit configured to control a frequency for the optical scanner to scan the laser light in the main scanning direction, and a light source driving unit. The scanner control unit multiplies the frequency by n and the light source driving unit changes time intervals at which pixels are rendered on scanning lines in the main scanning direction to 1/nth and controls the light source unit in such a way that the light source unit renders a plurality of pixels corresponding to one scanning line at least once during n scans in the main scanning direction and in such a way that the light source unit will not render pixels on scanning line(s) other than the scanning lines on which the pixels have been rendered.