An electrophotographic process cartridge and an image forming apparatus using such a process cartridge are provided. The process cartridge includes a casing member containing a photosensitive drum; a driven gear co-axial with the drum; a charging member, a developing member, and a cleaning member operable on the drum; and a protuberance adjacent one end of the drum and protruding outwardly of the casing member at one side thereof. An earth contact is provided by the protuberance at the one side of the casing member, and a charging bias contact and a developing bias contact are provided at an opposite side of the casing member and are disposed adjacent to and respectively forwardly and rearwardly of an axis of the drum relative to an insertion direction of the process cartridge into the image forming apparatus.