An image forming apparatus including a drive source, a rotating body, a processing unit, and a joint to switch transmission and disconnection of the driving force by moving along an axial direction, is provided. The joint is rotatable by the driving force transmitted from the rotating body in a coaxial position with respect to the rotating body and switches transmission and disconnection of the driving force by moving along the axial direction. The rotating body includes an input rotating body, which is subject to the driving force input in the rotating body and rotatable by the driving force, and an output rotating body, which is arranged coaxially with respect to the input rotating body and rotatable integrally with the input roller to output the driving force. The rotating body provides accommodating space, which accommodates at least a part of the joint when the joint is separated from the processing unit.