An image forming apparatus includes an image forming apparatus body including a driving force transmitting portion and a process cartridge. The process cartridge includes a housing, a photosensitive drum disposed in the housing, a first bearing rotatably supporting an axial end portion of the photosensitive drum, a driving force input portion, which is provided on the axial end portion of the photosensitive drum and is configured to engage the driving force transmitting portion in order to drive the photosensitive drum by a driving force transmitted from the driving force transmitting portion when the driving force transmitting portion is pressed against the driving force input portion, and a second bearing, which rotatably supports the other axial end of the photosensitive drum, and which comprises a first contact portion which contacts the image forming apparatus body when the driving force transmitting portion is pressed against the driving force input portion.