To easily and speedily determine the integer biases of carrier phases without positioning a reference station antenna and a mobile station antenna at temporarily provided points.

The mobile station antenna is arranged at a reference O point, and the reference station antenna A is arranged at an A point to observe the carrier phase of each satellite and obtain a double phase difference. The temporary integer bias of the double phase difference is obtained so that the results of the carrier differential positioning of the A point to the O point may become locational relationship obtained by individual positioning, etc. Then the mobile station antenna is moved to a B point to observe the carrier phases at the reference station and the mobile station, and a movement vector is obtained from the O point of the mobile station antenna through the use of the temporary integer bias. Then the reference station antenna is arranged at the O point to observe a double phase difference, and the integer bias of the double phase difference through the use of the observed double phase difference and the movement vector.