A sum of products calculation of a predetermined tap number of tap data and a prescribed tap number of coefficients is carried out and a sum of the predetermined number of tap data is calculated. A replica signal is calculated on the basis of the sum of products calculation result, the sum of the tap data, and a correction coefficient. A residual signal is calculated as the difference between the replica and received signals. The predetermined tap number of coefficients is updated based on the predetermined tap number of tap data and the residual signal, and the correction coefficient calculated from the residual signal. Here, the tap data is either a data symbol before the superimposition of a DC component or an estimation thereof. This allows an adaptive FIR filter used in channel estimation of a received signal by a digitally modulated wave whereupon a DC component is superimposed.