An image forming apparatus includes a rotary unit that has a rotary shaft, and a plurality of development devices each of which has a constituent unit, the development devices provided around the rotary shaft; and a plurality of state detection units that detects at least one of states of the development devices and states of the constituent unit; wherein the rotary unit is rotated so that the development devices sequentially pass a development position facing a photosensitive member; wherein when any of the development devices is located at the development position, the development device makes an electrostatic latent image on the photosensitive member visible; and wherein each of the state detection units detects at least one of the development devices and the states of the constituent unit during a single stop of rotation of the rotary unit.