PURPOSE: To simplify circuit constitution for muting and to attain stable muting control.

CONSTITUTION: An IF signal is fetched from the post stage of an amplifier 14a in an IF amplification part 14 and rectified and detected by a level detection part 21 to generate a DC signal I proportional to the level of the IF signal. The DC signal is sent to a muting control part 23. The control part 23 operates so as to turn on a muting switch 24 when the DC signal I is lower than a prescribed level, so that an audio output is short-circuit by earth and interrupted. Since the level of a noise component is low when the whole signal level in an IF band is high or the noise level is high when the signal level is low, muting is controlled by utilizing the above characteristics.