Patent ID: 8879955

Claim:
A drum unit comprising: a photosensitive drum including a hollow cylindrical drum sleeve having a surface on which a latent image is formed and bearing a toner image corresponding to the latent image, a flange press-fitted into an end portion of the drum sleeve and rotatably supporting the drum sleeve, and a supporting portion made of resin, protruding from a lateral face of the flange in an axial direction of the drum sleeve, and serving as a rotating shaft for rotation of the drum sleeve; a circular tube member made of metal, extending in the axial direction, and having a first inner peripheral surface forming a space, and a first outer peripheral surface that is opposite from the first inner peripheral surface; a housing rotatably supporting the photosensitive drum; and a bearing portion fixed to the housing, having a second inner peripheral surface facing the first outer peripheral surface and forming a space, wherein the supporting portion is press-fitted into the first inner peripheral surface of the circular tube member, and the circular tube member is inserted into the second inner peripheral surface of the bearing portion, and wherein the flange has a helical gear to which a rotational driving force or reaction force associated with a rotational driving force moving the photosensitive drum toward the outer side in the axial direction is imparted, and wherein the circular tube member has a flange portion protruding from the first outer peripheral surface toward the outer side in a radial direction of the drum sleeve and located between the bearing portion and the lateral face of the flange in the axial direction.