PURPOSE: To surely transmit and receive a signal and to improve the reliability of a radio system by constituting a home security device so that at the time of transmitting and receiving the information obtained by various sensors, a signal of its information is brought to double modulation/demodulation, and also, transmitted by a diversity system.

CONSTITUTION: A transmitting part 2 is provided with a sensor input detecting part 4 for detecting a signal of information obtained by various sensors 1 and making it triple, an MF modulating part 5 and an FSK modulating part 6 for bringing this triple signal to clouble modulation of FM/FSK (Frequency Modulation/Frequency Shift Keying), and a diversity switching part 7 for outputting the double modulating signal by a diversity system. From the transmit ting part 2, fire information, etc., are transmitted by the diversity system, and also, brought to triple transmission. On the other hand, in a receiving part 3, the double modulating signal is demodulated, and also, the demodulated triple transmitting signal is set to one signal by a majority system. In such a way, the information by various sensors 1 is transmitted and received surely, and the reliability of transmission and reception by a radio system can be improved.