A process cartridge has an electrophotographic photosensitive drum, a charging roller for charging the drum, a spacer movable between a separation position for separating the roller from the drum and a contact position for contacting the roller to the drum, a rotatable receiving gear for receiving a driving force produced by rotation of the drum to move the spacer from the separation position to the contact position, and a rotatable transmission gear engaged with the receiving gear and the spacer to transmit the force from the receiving gear to the spacer to move the spacer from the separation position to the contact position, wherein play is provide in the engagement portion between the receiving gear and the transmission gear so that they can be freely rotated relative to each other by a predetermined angle, whereby the drum is not reversely rotated when the roller is separated from the drum.