PURPOSE: To recover a low frequency component with simple constitution even for a multi-value signal by using an integration circuit having a time constant equal to that of a transmission line to integrate an error signal at the time of identifying a level and feeding the result back to an input of an identifier.

CONSTITUTION: A reception signal is amplified to have a peak value corresponding to a multi-value level by an AGC amplifier 1 so as to form a peak value within a prescribed range of the identification level in an A/D converter 2. Furthermore, the error signal from the A/D converter 2 is integrated by the integration circuit 3 to form an integration output signal having a waveform corresponding to that effected by the transmission line, the signal is added to a reception signal by an adder 4 in the polarity correcting the waveform distortion of the reception signal to recover the low frequency component, and since the error signal is controlled to be zero in average, a prescribed low frequency component is recovered even for a multi-value signal.