To efficiently dissipate heat being generated by an electronic circuit unit and at the same time secure waterproofness by using a resin case.

A case 8 for accommodating an electronic circuit unit 7 where electronic parts including a heat-generating part 10 are mounted at a circuit board 9 is made of resin, a metal bracket 13 is arranged outside the case 8 so that it opposes a heat-collecting plate 12 of the heat-generating part 10 of the electronic circuit unit 7, and the bracket 13 and the heat-collecting plate 12 are allowed to touch directly each other through an opening 14 being formed at the resin case 8. A recess/protrusion engagement part 19 is provided between the bracket 13 and the resin case 8 so that the opening 14 can be surrounded, and at the same time a packing 18 is provided between the recess/protrusion engagement part 19 and the head part of a bolt 17 for forming waterproof structure.