An image forming apparatus includes a fixing device which includes a fixing unit including an endless fixing belt, a heating portion, and a temperature detecting portion and which includes a nip forming member; a first storing portion; and a controller. In a case that a predetermined part of a plurality of parts is exchanged, the controller succeeds information other than information on the predetermined part of information on the fixing device stored in the first storing portion, and determines a target temperature in temperature adjustment control by using the succeeded information and information on the predetermined part used after being exchanged.