An image forming apparatus is capable of forming a clear image by using laser beams projected from a plurality of laser light sources. The image forming apparatus forms an electrostatic latent image on a medium to be scanned by laser beams, which are projected from a plurality of laser light sources and periodically deflected by a rotational deflecting unit, so that the laser beams scan the medium, which is uniformly charged and moving in a sub-scanning direction, in a main-scanning direction perpendicular to the sub-scanning direction. A pixel clock generating unit generates pixel clocks, which are used for controlling timings of projection of the laser beams, separately for each of the laser light sources, and for performing a phase change of each of the pixel clocks; and a phase control unit that controls independently each of the pixel clocks.