A position detection system and a position detection method in which the accuracy of position measurement of a device is not decreased after a change in the resonant frequency of a magnetic induction coil are provided. The position detection system includes a device having a magnetic induction coil a driving coil that generates an alternating magnetic field, to be applied to the magnetic induction coil, having a position-calculating frequency in the vicinity of a resonant frequency of the magnetic induction coil a plurality of magnetic sensors that detects an induced magnetic field generated by the magnetic induction coil when the alternating magnetic field is applied thereto a measurement-reference-value calculating section (50d) that determines a measurement reference value at the position-calculating frequency, based on an output of the magnetic sensors when only the alternating magnetic field is applied thereto a position-analyzing section (50e) that calculates at least one of the position and orientation of the device, based on a difference measurement value that is a difference between an output of the magnetic sensors when the alternating magnetic field and the induced magnetic field are applied thereto and the measurement reference value and a redetermining section (50b) that redetermines the position-calculating frequency at a predetermined timing.
