A position detection system for detecting a position of a capsule medical device is provided. The capsule medical device has a coil constituting a part of a resonance circuit to generate an AC magnetic field. The position detection system includes: sensing coils that detect the AC magnetic field and output detection signals; and a calculation unit that calculates the position of the capsule medical device based on the detection signals. The calculation unit: determines a sensing coil having a maximum amplitude of the AC magnetic field as a reference coil among the sensing coils based on amplitude values of the AC magnetic field detected by the sensing coils, the amplitude values being calculated based on the detection signals; and determines a polarity of each sensing coil based on a first detection signal from the reference coil and a second detection signal from each sensing coil other than the reference coil.