To reduce power consumption by executing synchronization with a GPS (Global Positioning System) signal at high speed.

A portable terminal receives spectrum diffusion signals S10 from a base station of a CDMA (Code Division Multiple Access) cellular system synchronized with GPS signals S1 transmitted from a GPS satellite, produces system time signals S17 as reference signals used for synchronizing with the GPS signals S1 based on the spectrum diffusion signals S10, receives the GPS signals S1, and gains synchronization with PN code in the GPS signals S1 based on the system time signals S17. By this, the achievement of synchronization with the PN code in the GPS signals S1 can be executed in a short time in accordance with the system time signals S17 and so power consumption can be much reduced.