An image forming apparatus for forming a color image on a recording material includes mounting means for detachably mounting a plurality of process cartridges each including a photosensitive drum and a developing roller. Movable members are provided that are actable on first and second clutches for switching between an operation state for transmitting the driving force to the developing rollers and a non-operation state not transmitting the driving force thereto. Also provided is a switching member for switching among a first mode for transmitting the driving force to the developing rollers of all of the process cartridges, a second mode for not transmitting the driving force to any one of the developing rollers, and a third mode for transmitting the driving force only to the developing roller of a black process cartridge.