To provide a digital demodulator having an automating type filter having a small number of taps as compared with a delay time to be corrected.

The digital demodulator comprises a filter M section 1M and a filter S section 1S having FIR filters, respectively. The section 1M inputs an input signal D as it is. The section 1S inputs an input signal D delayed via a variable shift register 11. Thus, a transmission distortion is, for example, corrected only in a section having a main wave and a reflective wave. Accordingly, the number of the taps of the FIR filter may be reduced as compared with the case that the distortion is corrected in the entire region. As a result, a circuit scale can be greatly reduced.