An image forming apparatus including an electrostatic latent image carrier, a plurality of development units each accommodating a toner to develop the electrostatic latent image, a development unit holder for holding the development units, and a control unit for controlling operation of the development unit holder and for selectively changing over the development unit. An identifying device identifies toner color information and the development unit holder is capable of holding at least two development units accommodating toner of a same color. The control unit identifies development units of the same color based on color information identified by the identifying device, and controls operation of the development unit holder to effect monochrome development by using the at least two development units.