A process cartridge detachably mountable to a main assembly of an image forming apparatus includes an image bearing member; a developer carrying member for developing an electrostatic image on the image bearing member; a first gear provided on the developer carrying member and a second gear driving-connected to the first gear; and a supporting portion for rotatably supporting the second gear. The supporting member is mounted on a frame of the process cartridge through a vibration damping member having a vibration transmission performance lower than that of at least the supporting portion.