A position detecting apparatus for a medical device includes a transmission unit configured to transmit a magnetic field in each of a plurality of frame periods. A reception unit detects the magnetic field transmitted from the transmission unit and output a detection signal corresponding to a position of the transmission unit. A signal control unit causes the transmission unit to transmit the magnetic field by a multiplexed signal including at least two or more different frequencies in a certain frame period among the frame periods, and causes the transmission unit to transmit the magnetic field by the multiplexed signal in the frame periods other than the certain frame period when the detection signal output from the reception unit has changed to a certain threshold or higher.
