PURPOSE: To improve the S/N of a magnetic recording/reproducing device by fetching a high frequency disturbance signal via an HPF to compare it with the reference level and cutting off the voice output when said disturbance signal is higher than the reference level by the fixed value or more.

CONSTITUTION: An external high frequency disturbance signal is fetched through an HPF 5a of a detecting circuit 5 out of the magnetic recording/reproducing output via an antenna, etc., and then turned into the voltage value corresponding to a due level by an envelope detecting circuit 5b and a rectifier circuit 5c. Then said voltage value is compared with a level set by a reference level setting circuit 6 and then muted by a muting circuit 8 with the output of a comparator circuit 7 if the voltage value is higher than the set level. Then the magnetic recording/reproducing output received via a signal processing part 3 is cut off to eliminate the influence of the high frequency disturbance signal together with improvement of the S/N. Thus it is possible to keep a radio wave rule, e.g., VDE0872TEIL4, 5, etc., of an FTZ standard of West Germany.