To achieve size reduction and cost reduction of a mounting board by avoiding trouble caused by a rise in temperature of a mounted electronic component and decreasing the number of external components.

The wiring board 30 mounted with the electronic component 40 has a switch element portion 21 interposed in a signal transmission line including a wiring layer 13 connecting with an electrode terminal 41 of the electronic component 40. The switch element portion 21 has a structure changing in shape depending upon temperature, and blocks the signal transmission line when the temperature exceeds a predetermined temperature. On a bottom portion of a cavity CV formed on an electronic component mounting surface side of the wiring board 30, a conductor layer 22 is formed which forms a portion of the signal transmission line. One end of the switch element portion 21 is fixedly connected to the wiring layer 13, and the other end is in contact with the conductor layer 22 when the temperature is below a predetermined temperature.