A drum unit is provided. The drum unit includes a frame, a photosensitive drum that is rotatably supported by the frame, a contact member that is held to the frame and that contacts a circumferential surface of the photosensitive drum. The circumferential surface of the photosensitive drum has an image forming area on which an electrostatic latent image is formed and a non-image forming area that is adjacent to the image forming area. The contact member is in surface-contact with the non-image forming area and is not contacting with the image forming area.