An image forming apparatus includes a main body and a fixing unit. The fixing unit is attachable to and detachable from the main body. The fixing unit includes a heating roller, a pressure roller, and a pressing member. The pressing member presses the pressure roller against the heating roller. The main body includes a cam and a slope member. The cam changes a pressing state of the pressing member. The slope member guides a lower end of the pressing member to a topmost part of the cam in attachment of the fixing unit to the main body.