To hold synchronization without outputting useless data as a correlation value and to output useful data even in the case that sudden phase change occurs on a transmission line in communication equipment using a CDMA(code division multiple access) system.

This correlator 11 is provided with first and second delay devices 14-1 and 14-2. An adder 15 adds the output signals of the first and second delay devices 14-1 and 14-2 and the input signals of the first delay device 14-1 and then, perform inverse spread and correlation value computation based on a phase detected in a synchronization part 13. Even when the phase of the input signals of the correlator 11 is changed by ±1 chip from the phase detected in the synchronization part 13, since signals to be inversely spread originally are inputted to the adder 15 from the input side of the first delay device 14-1 or the output side of the first delay device 14-2, a correct correlation value is obtained.