A final located position when a GPS receiver section (positioning section) has finished positioning is determined to be the latest located position, and the combination of identification information (ID) of base stations (suspended base stations) with which a portable telephone wireless communication circuit section has performed wireless communication is stored in a flash ROM. The combination of base stations that currently perform wireless communication with the wireless communication section and the combination of the suspended base stations stored in the flash ROM are compared when the GPS receiver section again performs positioning. When it has been determined that the combinations coincide, the latest located position stored in the flash ROM is estimated to be the present position of a portable telephone. The estimated present position is used as the initial position during the first positioning when the GPS receiver section again performs positioning.