The present invention provides an image forming apparatus including: a rotating body that holds recording medias on a circumferential surface; an image forming section that forms an image; a generating section that generates a pulse and a reference pulse; a measuring section that measures the number of pulses; a computing section that each time when predetermined number of pulses from generation of the reference pulse has been measured, divides a pulse width of a pulse before predetermined number of pulses by a first value to compute a pulse division time; and a controlling section that each time when predetermined number of pulses are measured from generation of the reference pulse, multiplies the pulse division time by a second predetermined value, thereby obtaining a forming start time, and that controls to start image formation when the forming start time has elapsed from the measurement of predetermined number of pulses.