A hermetically closed space S is formed in a case body 2 having watertightness, a drive part 5 and a power supply 6 are housed in the hermetically closed space S, the rotary shaft 5a of the drive part 5 is joined to the inner wall 2a of the case body 2, a plurality of equator parallel protruded parts 3 and a plurality of longitude line like protruded parts 4 are protruded on the outer peripheral surface of the case body 2 and the outer peripheral surface of the case body 2 is formed into an uneven shape by the equator parallel protruded parts 3 and the longitude line like protruded parts 4.