To provide a position measuring system combinedly using RTK and GPS-IMU to determine the minimum searching space capable of precluding a solution of an integer value bias from being excluded even when reception from GPS satellites is interrupted.

In this method, an output position of an IMU serves as a the center position, as to coordinates, a searching space using a positional error dispersion as a radius is set around the center position as the center, and the integer value bias is determined out of integer value bias proposals having the solution within the searching space, in the case where the integer value bias is determined when interruption of transmitted radio waves from the GPS satellites or a base station is restored, in a positioning method using an RTK/ GPS-IMU in combination using a positioning device using a combined RTK-IMU comprising a moving station having a GPS receiving part, a GPS correction data receiving part, an RTK positioning calculation part and the IMU, the base station, the plural GPS satellites.