An image forming apparatus includes a first image formation unit that forms a black toner image, and a detachable second image formation unit that forms a color toner image. A first toner supply unit is provided to supply the black toner to the first image formation unit. A second toner supply unit is provided to supply one of a black and component color toner to the first and second image formation units in accordance with a color mode. A first conveyance path is provided to convey the black toner to the first image formation unit. A second conveyance path is also provided to convey the component color toner stored in the second toner container section to the second image formation unit. The second toner supply unit is selectively connected to one of the first and second conveyance paths in accordance with the color mode.