A process cartridge is detachably mountable to a main assembly of an electrophotographic image forming apparatus that includes a cam movable between first and second positions. The cartridge includes an electrophotographic photosensitive drum, a developing roller developing an electrostatic latent image formed on the drum, a first frame for supporting the drum, a second frame for supporting the roller and connected with the first frame for relative rotation about a shaft disposed downstream of the roller with respect to a cartridge mounting direction, an entering portion at one end of the second frame with respect to a drum longitudinal direction and downstream of the shaft with respect to the mounting direction, permitting at least a part of the cam to enter when the process cartridge is mounted to the apparatus, and a cam engaging portion engaging the cam to receive a force for spacing the drum and the roller from each other.