An image forming apparatus includes a rotary unit having a plurality of development devices provided around a rotary shaft, the development device having a constituent unit, wherein: a plurality of the development devices sequentially move to a development position, where the development devices oppose an image carrier by rotation of the rotary unit, and a development device located at the development position develops an electrostatic latent image on the image carrier; each of the plurality of development devices has a state detection unit that detects at least one of a state of the development device and a state of a constituent unit of the development device; and the state detection unit of each of the development devices performs state detection when the development device having the state detection unit is located at the development position.