A pressing member applies a pressing force to a trailing end in a direction which intersects a predetermined reference direction, allowing the pressing force to have both a first component in the predetermined reference direction and a second component perpendicular to the predetermined reference direction. A trailing end is pressed in the predetermined reference direction by the first component. In the mounted state, the leading end is in contact with the reference member at two contact surfaces including a first contact surface and a second contact surface. The first contact surface defines a first positioning direction being perpendicular to the first contact surface and intersecting the predetermined reference direction. The second contact surface defines a second positioning direction being perpendicular to the second contact surface and intersecting both the predetermined reference direction and the first positioning direction, allowing the photosensitive-member unit to be positioned with respect to the main body.