To provide a demodulator used in a digital communication system, capable of improving reception quality by suppressing intersymbol interference to have strong characteristics with respect to multipath.

This digital communication system for transmitting digital information is provided with a transmission line characteristics estimating means for estimating the impulse response of a transmission line from a received signal, a plurality of waveform equalizing means consisting of a first to N-th waveform equalizing means, an optimum waveform equalizing means deciding means for deciding an optimum waveform equalizing means among the plurality of the waveform equalizing means by using an impulse response estimated value of the transmission line obtained by the transmission line estimating means, and a demodulating means for demodulating a waveform equalization signal from the optimum waveform equalizing means. The plurality of the waveform equalizing means are a plurality of a 1st to the N-th waveform equalizing means, that operate so as to demodulate the energy of a single relevant incoming wave among 1st to the N-th incoming waves of digital information.