A waveform equalizer having a delay element of a feed-forward filter into which a reception signal is inputted is connected via a tap arrangement control switch to a weighting device The output of the weight device is inputted into an adder. The output of the adder is entered into a discriminator to become an equalization output. The equalization output is entered into a delay element of a feed-back filter. The delay element is connected via the tap arrangement control switch to the weighting device. The tap arrangement control switch ON/OFF-controls the tap arrangement. The tap coefficient monitoring unit monitors the tap coefficients of the weighting device. When the equalization operation cannot be carried out, it is restarted from the beginning of the reception signal. An impulse response predictor predicts an impulse response of a transfer path based upon the reception signal and the equalization output.