To facilitate flow of a melted and softened rubber material during rubber vulcanization for molding so as to provide a uniform rubber matter by forming a projection part, which is protruded on an elastic member side from a reinforcing member through hole in an attaching/detaching means, into a circular flat shape and bringing the projection part close to the reinforcing member.

An attaching/detaching means is constructed of a bolt 4, which is protruded in one end of a reinforcing member 2, and a nut. The bolt 4 is formed of a head part 4a, which is a projection part protruded toward a rubber pad 1 side from a through hole 2a in the reinforcing member 2, and a screw part 4b. The head part 4a, which is thinned as much as possible, for example, thinned to 4 mm while taking a cost for welding into consideration, is brought close to the reinforcing member 2 face and is formed into a circular disk shape as it is not rotated. In vulcanization for rubber pressing molding, the reinforcing member 2 and the head 4a are heated at substantially same temperature and are molded into substantially uniform rubber matter as a whole. As the head 4a positioned in the corner does not disturb a passage for the rubber material, and the melted and softened rubber material is smoothly extruded and spread evenly to every corner of a die, and as a result, uniform rubber matter can be obtained.