PURPOSE: To cope with the optional roll-off characteristics at a high speed by selecting the tap coefficients applied to the front-back codes of each code of an input signal out of plural types via a selector and compensating the code interference to acquire a roll-off filter for received data.

CONSTITUTION: A selector 1 can give (n+1) types of changes including the non-change to the bit number (n) of the tap coefficient (1/2)n against the value of an original input signal Xn with use of a control signal SEL. Therefore the symmetrical additions are performed with the fixed number of stages 2m+1 only with use of plural types of tap coefficients in case the arithmetic operations are applied to the output signals X11∼X1m (m: constant bit) of the selector 1 by means of a delay unit 2 and an adder 3. Then the code interference to be applied to a code Xo from the front-back codes Xo-m and Xo+m is compensated in plural types. Thus the code waveform of an input signal can be shaped. As a result, it is possible to cope with the optional roll-off characteristics at a high speed and at the same time to select the tap coefficients with a margin.