A protrusion 53 is shaped to protrude from a main body 51 toward a supporter non-contact part 23 so as to circumvent a supporter 30. The protrusion 53 includes a protrusion heat transfer surface 55 which is a surface on the battery heat transfer surface 20 side (i.e., an upper side Y2). A heat conduction member 40 contacts with the supporter non-contact part 23 and the protrusion heat transfer surface 55.