An image forming apparatus includes a controller controlling a movement of a moving member to successively move a plurality of developing devices to a developing position in an image forming operation. A moving distance in at least one moving operation is different from a moving distance in other moving operations. A controller performs at least one moving operation and other moving operations during a transfer operation by a primary transferring device. The controller controls a moving speed of the moving member so that a relative position of a trailing edge of an image forming region on the image bearing member with respect to the developing position is controlled for the at least one moving operation and the other moving operations and so that the moving speed is uniform when the moving member performs a developer supplying operation in a non-image forming operation.