An image forming apparatus includes an image forming unit including a latent image carrier, a charging device, a latent image writing device, and a development device; a cumulative value calculation device that calculates, for each of regions of a surface of the image carrier, a cumulative value of the area of a latent image formed in the region; a surface potential detector that detects the surface potential of the image carrier in one of the regions as a detection region; and a determination device that determines the deterioration degree of the detection region on the basis of the detected potential, and determines the deterioration degree of a region other than the detection region on the basis of the detected potential, the cumulative value for the detection region, and the cumulative value for the region other than the detection region.