PURPOSE: To enable the detection of the correct position of the rolling stock regardless of a phase changes of a ground coil by a method wherein a search coil based on a reaction high harmonic wave magnetic flux which generated by the ground propulsion coil is mounted on the rolling stock and the output thereof is made as a position signal.

CONSTITUTION: The search coils 7A, 7B for detecting a tertiary time harmonic voltage are mounted on the rolling stock and the output thereof is transmitted to the ground thrugh an antenna 9 from a transmission unit 8 and received at a receiving means 10. A terminal voltage of the ground propulsion coil 3 is detected at a propulsion coil detection unit 11. The propulsion coil detection unit 11 detects coil terminal voltages in U-shape and V-shape and generates a rectangular wave corresponding to a U-phase positive boltage region and a rectangular wave corresponding to a V- phase negative voltage region, and the generated rectangular waves are fed to a comparator 12. AND of a rising pulse and the rectangular waves is taken in the comparator 12 to obtain the position signal. Thereby, the position of the rolling stock can correctly be detected without requiring the detector for detecting the position on the ground.