To provide a position detecting system including a detected object disposed in a detection space and an external device disposed outside the detection space. The detected object includes a resonant circuit that generates a resonant magnetic field according to a driving magnetic field formed in the detection space, and the external device includes at least two drive coils that form the driving magnetic field in the detection space, at least two drive-signal input units that respectively input a drive signal for forming the driving magnetic field to the drive coils, at least one sense coil that detects a magnetic field formed in the detection space, a signal adjustment unit that adjusts a phase and an amplitude of the drive signal input to each of the drive coils by the drive-signal input units, based on a magnetic field detected by the sense coil, and a position deriving unit that derives a position of the detected object based on the magnetic field detected by the sense coil.