Provided is a position detection system capable of determining a polarity of a sensing coil without complicating a configuration of a capsule medical device. The position detection system includes a plurality of sensing coils 32(i) which detect AC magnetic field generated from a marker coil and output detection signals and a calculation unit 46 which calculates a position of a capsule endoscope 10 based on the plurality of detection signals output from the plurality of sensing coils 32(i), in which the calculation unit 46 includes a reference coil determination unit 462 which determines the sensing coil having a maximum amplitude value of the AC magnetic field as a reference coil among the plurality of sensing coils 32(i) based on amplitude values of the AC magnetic field which are calculated based on the plurality of detection signals and are detected by the plurality of sensing coils 32(i) and a polarity determination unit 463 which determines polarities of the sensing coils 32(i) based on a first detection signal output from the reference coil and second detection signals output from the sensing coils 32(i) other than the reference coil.
