A frequency offset correcting unit estimates frequency offsets in a preamble period, corrects digital received signals by the estimated initial frequency and further corrects them by residual frequency signals. A receiving weight vector computing unit computes receiving weight vector signals by using LMS algorithm. Based on the error vectors or receiving weight vector signals derived by LMS algorithm, the frequency offsets contained in corrected received signals are also estimated and are outputted as the residual frequency signals. A multiplier weights the corrected received signals with the receiving weight vector signals. An adder sums up outputs of the multiplier so as to output a synthesized signal.