An image carrier is adapted such that an electrostatic latent image is formed thereon. A rotary member has a plurality of loading sections each of which is adapted to accommodate a developing device which is operable to develop the electrostatic latent image. A motor is operable to rotate the rotary member so that each of the loading sections is sequentially opposed to the image carrier, and operable to exert a detent torque when no power is supplied thereto. A home position is defined, in a case where only one of the loading sections accommodates the developing device, such that the one of the loading sections is placed in a position lower than any other loading sections. The motor rotates the rotary member to the home position at least when the development of the electrostatic latent image is not performed. The rotary member is retained in the home position with the detent torque exerted by the motor.