A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus includes an electrophotographic photosensitive drum, a process device actable on the drum, and a movable operation member. After the cartridge is mounted to the main assembly of the apparatus, the movable operation member is displaced by a driving force transmitted from the main assembly of the apparatus to the cartridge, so that the movable operation member is engaged with a displaceable member provided in the main assembly to move the displaceable member, in interrelation with which an output contact of the apparatus is moved from a retracted to an electrical connection position against an elastic force of an elastic function member. In addition, the cartridge includes an input electrical contact for receiving a voltage for enabling the process device means by engagement with the output contact moved to the electrical connection position.