In an image forming apparatus, a control device recognizes expansion and contraction of a pattern image based on an output of an image detector. The control device calculates a driving motor velocity fluctuation cancellation pattern for driving a common drive source. The driving motor velocity fluctuation cancellation pattern creates a latent image expansion and contraction cancellation pattern capable of canceling the expansion and contraction of the pattern image detected by the image detecting device. A process of obtaining the cancellation patterns is executed except when a print job for forming the toner image is executed in accordance with image information. The control device controls the common drive source in accordance with the cancellation driving motor pattern.