PURPOSE: To make a circuit scale small and to reduce a calculation amount by providing a successive equalization part using successive decoding algorithm.

CONSTITUTION: By a received training series, the impulse response CIR of a propagation line is calculated in a propagation line impulse response calculation part 1. A replica generation part 2 generates replica signals based on the impulse response CIR of the propagation line and equalized output signals and a branch metric calculation part 3 calculates the square of the absolute value of a difference between the replica signals and reception signals through the propagation line as branch metric. A conversion table 4 converts the branch metric to Fano metric obtained from the distribution function of the branch metric for instance and the successive equalization part 5 equalizes the reception signals by applying the successive decoding algorithm such as the Fano algorithm and stack algorithm, etc.