A battery case as an electronic component case includes a second conductive plate made of metal, an insulating wall having an upper end surface and a bottom end surface, a first conductive plate made of metal joined to an upper end surface of the insulating wall, and a second conductive plate attached to the bottom end surface of the insulating wall. The insulating wall has a first conductor layer formed on an entire perimeter of the upper end surface thereof and a second conductor layer formed on an entire perimeter of a lower surface thereof, an electrode formed at a peripheral portion of the lower surface of the insulating wall so as to be electrically independent from the second conductor layer, an external connection terminal brazed to the electrode, and a connection conductor formed from the first conductor layer to the electrode. The first conductive plate is attached to the insulating wall via the first conductor layer. The second conductive plate is attached to the insulating wall via the second conductor layer.