To deeply set squelch opening sensitivity by preventing squelch from being opened due to the erroneous recognition of any carrier which is present in an adjacent channel.

A demodulated output signal, outputted from an FM demodulating circuit 1, is waveform-shaped by a waveform shaper 6, and the FM demodulated output signal is inputted to a band pass filter 3 so that noise components can be detected, and the output of the band pass filter 3 is smoothed by a smoothing circuit 4. In this case, when it is detected that a counted value obtained by counting the waveform shaped output in a decided prescribed time beforehand is less than a preliminarily decided counted value, and that the level of the smoothed output from the smoothing circuit 4 is less than a decided set level beforehand a squelch switch is controlled so as to be turned on by a control circuit 8.