A position detecting system (11a41) includes a magnetic field generator (10), a detecting body (242), a magnetic field detector (13), a position/direction calculating unit (15), and a control unit (1959). The magnetic field generator generates a magnetic field in a three-dimensional space. The detecting body is put into the three-dimensional space, and includes a resonance circuit for generating a resonance magnetic field. The position/direction calculating unit calculates a position/direction of the detecting body. If the resonance circuit is in the non-resonant state, the magnetic field detector detects an environmental magnetic field, and the control unit updates detection data of the environmental magnetic field. If the resonance circuit is in the resonant state, the magnetic field detector detects the spatial magnetic field in the three-dimensional space. The position/direction calculating unit executes processing using the detection data of the spatial magnetic field and updated detection data of the environmental magnetic field.
