PURPOSE: To improve frequency characteristics by preventing a magnetic recording medium from being saturated in a high frequency range, by providing a limiter circuit which operates when a high-frequency signal increases above a constant level.

CONSTITUTION: A signal applied to an input terminal 1 is amplified by a recording amplifier 2 and then supplied to an equalizer amplifier 3. The high-frequency signal, passed through a high-pass filter 6 in a limiter circuit 5, of the output of the equalizer amplifier 3 is amplified by a level detecting amplifier 7 and converted by a rectifier 8 into a DC signal, which is amplified by a DC amplifier 9. As a result, the impedance of a variable impedance circuit 10 is varied by a DC signal level from the DC amplifier 9. When the high-frequency level of the input signal rises above some value, control is so exercised that the output of the qualizer amplifier 3 is constant. When the high-frequency level component is at a level below the value, the equalizer amplifier 3 has high-frequency emphasis characteristics.