A process cartridge detachably mountable to a main assembly of an image forming apparatus, said process cartridge comprising: a photosensitive drum; a rotatable developing roller configured to develop an electrostatic latent image formed on said photosensitive drum; a rotatable developer supplying roller provided in contact with said developing roller and configured to supply a developer to said developing roller; a developer accommodating chamber configured to accommodate the developer; a developing chamber in which said developer supplying roller is provided; a rotatable feeding member provided in said developer accommodating chamber and configured to feed the developer from said developer accommodating chamber into said developing chamber by moving the developer upwardly against a gravity; a driving force receiving portion provided on said developer supplying roller and configured to receive from an outside of said process cartridge a driving force for rotating said developer supplying roller, said developing roller and said feeding member; a first driving force transmitting portion provided on said developer supplying roller and configured to transmit the driving force received by said driving force receiving portion to said developing roller; and a second driving force transmitting portion provided on said developing roller in engagement with said first driving force transmitting portion to transmit the driving force from said first driving force transmitting portion to said developing roller, wherein said developer supplying roller and said developing roller are rotatable such that surfaces of said developer supplying roller and said developing roller move from a contact portion therebetween toward a bottom of said developing chamber, and wherein a peripheral speed of the surface of said developer supplying roller is higher than that of said developing roller.