PURPOSE: To decrease the power consumption, by applying a power supply for a reception processing circuit, only when a modulation frequency signal is detected.

CONSTITUTION: A signal consisting of sequential combination of a plurality of modulation frequency signals is received and inputted to a processor 10 through a front end circuit 4, amplifying circuit 5, filters 6∼9. The processor 10 interpretes the sequential combination of signals from the filters 6∼9, and the output controls a load 3. On the other hand, a signal from an amplifying circuit 5 is discriminated for the level at a level discrimination circuit 11 to detect frequency modulation signals, and a switch drive circuit 12 is activated with this detected output. A switch 14 is inserted between a DC power supply 13 and the processing circuit 10 in interlocking with a switch drive circuit 12, which switches the switch 14.