PURPOSE: To automatically set an optimum equalizer characteristic by supplying a signal corresponding to the output level of a first holding circuit to an equalizer at an amplification rate smaller than that of a first amplifier.

CONSTITUTION: The device consists of BPF (band pass filter) 11 and 12, whose center frequencies are 1.57MHz and 4.7MHz, detection circuits 13 and 14, change over switches SW1 and SW2, holding circuits 15 and 16, an attenuator 17, a subtracter 18, inversion amplifiers (operand amplifiers) 19 and 20, a signal processing circuit 22 and the like. Then, respective frequencies are detected and are fed back so that 'basic wave-third higher harmonics' being the output of the subtracter 18, namely, 'H1/3' always becomes constant. When a reproduc tion output is too small, only the output voltage (basic wave component) of the holding circuit 15 is taken out for restricting the feed back gain and the inversion amplifier 20 suitably amplifies it. Then, the output voltage is reduced as against the gain of a loop and is supplied to the control terminal of the equalizer 9. Thus, the equalizer characteristic is always held in optimum.