A process cartridge is detachably mountable to a main assembly of an electrophotographic. The cartridge includes a photosensitive drum; a process device; and a first contact portion provided on a bottom surface of a cartridge frame provided at one longitudinal. The first contact portion is guided by a first assembly side guide when the cartridge is mounted. The cartridge also includes a cartridge coupling disposed above the first portion, the coupling being engageable with an assembly side coupling to receive a rotational force from the assembly; and a second contact portion disposed behind the first portion with respect to the mounting direction. The second portion limits rotation of the cartridge. The cartridge also includes; a positioning portion projected outwardly and provided at the other longitudinal end of the drum, the positioning portion being guided by a second assembly side guide, and being positioned to a second assembly side receiving portion.