A heat dissipating member has an inner wall, outer wall, and partition walls. The inner wall directly or indirectly receives heat transfer from the heat source. The outer wall opposes the inner wall at a distance. The partition walls connect the inner wall and the outer wall. The inner wall, the outer wall, and the partition walls define a plurality of through-holes along the inner wall and the outer wall. Each of the through-holes extends in a vertical direction within a tilt range in which gravitational influence is utilizable. Upper and lower ends of each of the through-holes open to the outside. Generated heat from the heat source is propagated to the outer wall via the inner wall and the partition walls. A predetermined amount of heat generated by the heat source passing through the outer side of the outer wall is determined so that rise in temperature of the outer side relative to the ambient temperature can be kept under a predetermined value.