PURPOSE: To obtain an adaptive automatic equalizer which is prevented from deteriorating in bit error rate by correcting a frequency offset.

CONSTITUTION: An input signal is stored in a buffer memory 11, signals of plural frequencies in a specific range are modulated in order by a modulator 12 with a training signal read out of the memory 11 as a carrier, and the modulation output is sent out through a filter part 14. A subtraction output obtained by subtracting the output training signal of a training signal generation part 17 from the output is added for each carrier frequency, the minimum value in the addition output is retrieved, and an initial value estimation part 25 estimates an initial value on the basis of the carrier frequency corresponding to said minimum value. Then a frequency offset estimation part 26 obtains a unit vector of a phase angle based upon equivalent error data by using the estimated initial value as an initial value and the output of the filter part 14 is corrected with the unit vector.