To provide a downsized structure of a mounting space in which a fuse element is not thermally damaged and can be safely supported even if a lead conductor of a temperature fuse is soldered vertically to the rear face of the temperature fuse immediately underneath the temperature fuse body, and therefore soldering is performed in a mounting exclusive space of the temperature fuse body.

A heat radiation part or a heat sink 3 is provided near the arrangement position of an exothermic circuit element of a wiring board 1 on which the exothermic circuit element 2 is mounted, and a prescribed lead conductor 21 of the exothermic circuit element 2 is soldered and connected to the heat radiation part or the heat sink 3, and the prescribed lead conductor 51 of the temperature fuse 5 is soldered and connected to the heat radiation part or the heat sink 3.