Abstract: A channel evaluator acquires a change predicted value from a known symbol, and a compensator compensates for a first symbol using the change predicted value. A demodulator restores a portion corresponding to this symbol with another subcarrier. A replica generator acquires a transmission replica of the restored symbol. The channel evaluator performs complex division on the replica with the symbol to acquire an amplitude phase ratio. A detector compares the amplitude phase ratio with an amplitude phase ratio acquired immediately previously. In case where an elimination condition is satisfied, the detector disregards the amplitude phase ratio acquired currently and uses an immediately previous value instead, an averaging unit averages amplitude phase ratios to acquire a next change predicted value, and the compensator compensates for a next symbol using the change predicted value. Hereinafter, the sequence of processes is repeated.