A control portion controls a drive of rotation of an image carrier and registers a second index with a first index passing through a transfer position at real time at the time of image formation. Before starting the image formation, the toner image forming portion is controlled to adjust misalignment between the first index and the second index. Accordingly, the second index is formed at a position on the image carrier which is registered with the first index in advance, so that a large amount of control for compensating a large amount of phase misalignment is no longer necessary.