An image forming apparatus has a plurality of image forming stations capable of forming different images which are to be correctly registered and superimposed. Elimination of possible image misregistration in each image station is executed on the basis of the result of detection of register marks which are formed by each image forming station. The correction is executed at a timing which is independent from image forming sequences performed by each imgae forming station in accordance with image signals, e.g., during warming-up of the apparatus after the initial application of the power immediately after the input of image forming operation start instruction through a start key, or after completion of production of a predetermined number of copies counted from the last misregistration correcting operation.