A selector sequentially selects different coefficients during a time interval T. A plurality of coefficient multipliers multiply an input signal sampled at intervals T and coefficients selected by the selector. An input circuit selects, at interval T/2, an input signal supplied at intervals T. A pipeline type adder adds an output signal of the input circuit and output signals of the coefficient multipliers. An output circuit adds an output signal of the adder in an interval of T/2 and outputs the result of the addition as a signal of a period of T.