An electrophotographic photosensitive drum supporting apparatus for rotatably supporting a photosensitive drum includes a first supporting member having a first hole for supporting one end of the drum, and first and second surfaces on one side and the other side of the first supporting member relative to an imaginary plane passing through the axis of the drum, respectively. The first and second surfaces are inclined with respect to the plane so as to contact with the drum and are provided on the inner surface of the first hole. The apparatus also includes a second supporting member having a second hole for supporting the other end of the drum, and a third and a fourth surfaces on one side and the other side of the second supporting member relative to the plane, respectively. The third and fourth surfaces are inclined with respect to the plane so as to contact with the drum and are provided on the inner surface of the second hole. The apparatus also includes a plurality of process members provided in contact with the drum. The direction of the resultant force of a force acting on the drum by the plurality of process members is a direction in which the drum is urged against the first and second inclined surfaces and against the third and fourth inclined surfaces.