An endless belt member for an image forming apparatus includes an endless belt member body that contains a resin and conductive particles, an inner transparent film, a position detection member that is used to detect the position of the endless belt member body, and an outer transparent film, wherein the position detection member is sealed by the inner and outer transparent films, is provided on a part of an outer peripheral surface of the endless belt member body, and has side surfaces which are substantially perpendicular to the outer peripheral surface of the endless belt member body, and the inner and outer transparent films are welded to each other at portions, which is adjoining the side surfaces of the position detection member, of the portions that come into direct contact with each other.