A substrate provided in proximity to a case for improving heat radiation, and maintaining electrical insulation between the substrate and the case even when the substrate is warped, in the substrate having electronic parts mounted thereon and a case for housing the substrate. A case body of the case has a substrate placement surface for placing the substrate, the substrate placement surface is provided with a protruding portion protruding therefrom, and the substrate is fixed on the substrate placement surface, via a thermal interface material disposed on the substrate placement surface from a periphery of the protruding portion.