The A/D converter changes sampling timing of a received signal in a synchronization acquisition mode and a synchronization tracking mode. The A/D converter generates an internal clock of a sampling frequency eight times a symbol rate under the control of the clock control unit in the synchronization acquisition mode. On the other hand, in the synchronization tracking mode, the A/D converter generates an internal clock with a symbol point and one each point before and after the symbol point as sampling timing under the control of the clock control unit. The A/D converter further corrects the sampling timing of the symbol point based on the squares of the maximum value of a correlation value between the received signal and a reference signal and the absolute values of correlation values before and after the maximum value.