An image forming apparatus capable of minimizing local degradation of the image carrier and effectively preventing image defects due to resistance reduction and adhesion of release agent, without lowering productivity. The image forming apparatus includes an image making unit, having an image carrier, with plural image carrying regions, the image making unit adapted to cause the image carrying regions on the image carrier to carry images and then to transfer the images onto the sheet in a series of image making cycles, and an image making controller for controlling the image making unit according to job commands for making images. The image making controller includes a reference signal changing circuit for changing reference signal for each job, and the reference signal determines which of the image carrying regions on the image carrier should be an image writing position.