PURPOSE: To prevent generation of noise by providing an FM carrier level detecting means to an FM demodulator having a PLL circuit so as to stop the operation of the PLL circuit when a carrier level is missing.

CONSTITUTION: An FM demodulation signal A is inputted to a terminal 5. The signal A is compared with an output of a voltage controlled oscillator VCO2 at a phase comparator 1. An output of the comparator 1 is inputted to a low-pass filter 3 via a switch 7. An output of the filter 3 is amplified by a buffer amplifier 4 and fed to the VCO2 and also fed to an output terminal 6 as a demodulated output. The signal A is fed also to a carrier level detector 8. When the carrier level is missing, the switch 7 is interrupted by a switching control circuit 9. The switch 7 is interrupted by a mute command.