To provide a position detection system capable of almost accurately detecting the three-dimensional position of a moving client by providing an altitude detection means for detecting the altitude of the moving client, a correction means indexing a two-dimensional measuring position on a map to correct the same and an arithmetic means for operating a height position on the basis of the output of the altitude detection means.

The position detection system for detecting the position of the moving client A using a GPS signal (a) is equipped with an azimuth detection means 5 for detecting an azimuth in order to correct position measuring data due to the GPS signal (a), the altitude detection means 6 for detecting the altitude of the moving client A, the correction means 23 for indexing the two-dimensional measuring position on the map and an arithmetic means 24 for operating the height position on the basis of the output of the altitude detection means 6.