This invention reduces electric power consumption of a CDMA communication system receiver in the wait mode. The received spread spectrum signal is demodulated in multiplication means 16 and 17 into baseband signals Ri and Rq, and input in complex matched filter 22. This filter is intermittently driven by supply voltage control means 20 to perform acquisition of received signals. When electric power calculation circuit 23 detects that outputs of this filter have a peak equal to or greater than a predetermined value, the received signals undergo acquisition by controlling n number of correlators 26-1 to 26-n to work by correlator controlling circuit 25; moreover, de-spreading is performed. Outputs from each correlator 26-1 to 26-n are given to RAKE combiner and demodulated by RAKE combining and demodulating circuit 28.