A radio wave transmitted from a mobile station 10 is received in each base station 12, and, based on the received power measured by a received power measuring portion 38 of the base station, a distance ratio calculating portion 54 of a position locating server 14 calculates the difference in the received power between the paired base stations. Based on the difference in the received power, the distance ratio is calculated between the distance from one base station to the mobile station and the distance from the other base station to the mobile station. A locus creating portion 56 of the position locating server 14 creates a locus which is a sequence of points showing positions where the calculated distance ratio is realized. The position calculating portion 58 calculates an intersection of the loci for a plurality of base station pairs, thereby calculating a candidate for the mobile station.