An electrophotographic photosensitive drum for use in an electrophotographic image forming apparatus includes a cylinder and flanges provided on end portions in the axial direction of the cylinder. One flange has an outer peripheral portion, a hole portion and ribs, and the flange is caulked by bending part of the cylinder inwardly in the radial direction at two positions opposing each other across the hole portion, those two positions being other than positions at which the ribs intersect the outer peripheral portion in the extending direction of the ribs.