To determine accurately the azimuth or the position of a moving body with a simple constitution.

A lateral G-value orthogonal to the progression direction of the moving body generated by a centrifugal force when a vehicle is turned is detected by a biaxial acceleration sensor 3 installed on the vehicle, and it is discriminated whether the vehicle is turned to the right or to the left based on the lateral G-value and prescribed thresholds TH1, TH2, and thereby the turning direction of the vehicle can be discriminated accurately with a simple constitution only by a single biaxial acceleration sensor 3 without using an angular velocity sensor.