To reduce heat drop as possible by fitting a temperature sensor directly to a heat generating circuit element for adhesion.

A heat-generating circuit element 1 is provided. A temperature sensor 2 which detects that the heat-generating circuit element 1 reaches a specified high temperature is provided. Further, a heat-shrinkable tube 4 for bundling both of them is provided. The operation temperature of the heat- shrinkable tube 4 is set lower than the specified high temperature, thus, shrinkage or the heat-shrinkable tube 4 begins first then the detection takes place.