A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the main assembly includes a first rotatable main assembly drive transmission member, and a second rotatable main assembly drive transmission member, said process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum with a developer; a drum coupling member, provided on one axial end of said electrophotographic photosensitive drum, for engaging with the first main assembly drive transmission member and transmitting a first rotational driving force to the electrophotographic photosensitive drum, when said process cartridge is mounted to the main assembly of the apparatus along an axial direction of said electrophotographic photosensitive drum; and a shaft coupling member, provided on one axial end of said developing roller, for transmitting a second rotational driving force with a deviation permitted between an axis of the second main assembly drive transmission member and an axis of said developing roller, wherein said shaft coupling member includes an engaging portion for engaging with the second main assembly drive transmission member and receiving the second rotational driving force, when said process cartridge is mounted to the main assembly of the apparatus; characterized in that said engaging portion is configured to be movable in a direction crossing with the axial direction of said developing roller, and wherein said process cartridge further comprises a holding portion (11c, 11f, 27f) configured to hold said engaging portion such that a rotational axis of said engaging portion is deviated from the rotational axis of said developing roller in the crossing direction. an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on said electrophotographic photosensitive drum with a developer; a drum coupling member, provided on one axial end of said electrophotographic photosensitive drum, for engaging with the first main assembly drive transmission member and transmitting a first rotational driving force to the electrophotographic photosensitive drum, when said process cartridge is mounted to the main assembly of the apparatus along an axial direction of said electrophotographic photosensitive drum; and a shaft coupling member, provided on one axial end of said developing roller, for transmitting a second rotational driving force with a deviation permitted between an axis of the second main assembly drive transmission member and an axis of said developing roller, wherein said shaft coupling member includes an engaging portion for engaging with the second main assembly drive transmission member and receiving the second rotational driving force, when said process cartridge is mounted to the main assembly of the apparatus; characterized in that said engaging portion is configured to be movable in a direction crossing with the axial direction of said developing roller, and wherein said process cartridge further comprises a holding portion (11c, 11f, 27f) configured to hold said engaging portion such that a rotational axis of said engaging portion is deviated from the rotational axis of said developing roller in the crossing direction.