Abstract: A plurality of ID transmitters that can issue an ID are provided in a building. A center station registers position information that allows identification of the position of an ID transmitter for every different ID. A PHS mobile terminal measures the received field intensity of each repeater and each ID transmitter. The measured result is sent to the center station. The center station identifies the position of the mobile terminal according to the measured result and the position information. Accordingly, the accuracy of the location of a mobile terminal can be improved without increasing the number of repeaters.