An image forming apparatus having a plurality of image carriers that are rotated in the same direction in synchronization with one another. The apparatus includes a detector that detects a rotational position on the each image carrier of the plurality of image carriers, a memory that stores a phase difference between a predetermined position and an eccentric position on each image carrier within the plurality of image carriers, and a controller that controls the eccentric positions on the circumferences of the image carriers to coincide with one another by using the phase differences stored in the memory.