To provide a more accurate mobile station position with improved accuracy.

A mobile station 20 transmits a measured value for which its own position is calculated from GPS signals and a track information ID used for calculation to a reference station 30 as measured value information. In the reference station 30, a track information storage part 34 and a previous time track information storage part 35 hold latest track information and the one before that obtained from the GPS signals. At the time of receiving the measured value information from the mobile station 20, a position calculation part 37 takes out the track information provided with the same track information ID as the one received from the mobile station 20 from the track information held in the track information storage part 34 and the previous time track information storage part 35 and calculates the position of the reference station 30, a correction value calculation part 43 obtains a difference between the calculated value and the accurate position of the reference station 30 stored in a reference station position storage part 40 beforehand and a mobile station position correction calculation part 44 introduces the difference to the calculated position of the mobile station 20 and performs correction calculation. As a result, the same track information is surely used.