PURPOSE: To eliminate reception noise due to sudden fluctuation of a reception electric field level.

CONSTITUTION: The circuit is provided at least with a smoothing section 1 smoothing an S meter output signal 101 received in response to a reception electric field strength and outputting the smoothed signal as a reference signal 102, a 1st comparator circuit 2 comparing a voltage level of the S meter output signal 101 with a voltage level of the reference signal 102 and outputting a prescribed logic value as a comparison output signal 103 when the voltage difference between them reaches a prescribed voltage or over, a 2nd comparator circuit 3 comparing a voltage level of the S meter output signal 101 with a voltage level of the reference signal 102 and outputting a prescribed logic value as a comparison output signal 104 when the voltage difference between them reaches a prescribed voltage or below, an OR circuit 4 receiving logic values outputted from the 1st and 2nd comparator circuits and outputting an ORed signal between the both, and a switch 5 receiving a received and demodulated audio signal 106, controlled by a control signal 105 outputted from the OR circuit 4 and implementing selection control whether or not an audio signal 106 is to be outputted.