A position detection system includes: a capsule medical device having therein a magnetic field generator for generating a magnetic field； magnetic field detectors for detecting the magnetic field and outputting detection signals； and a processor including hardware. The processor is configured to: calculate a position of the capsule medical device using at least one of the detection signals； determine whether or not proper position detection of the capsule medical device based on the detection signals is possible using a threshold that is a value based on at least one of output values of the detection signals output by the magnetic field detectors under a predetermined condition； decide a determination value using at least one of the output values of the detection signals； and determine that the proper position detection of the capsule medical device is not possible when the determination value is smaller than the threshold.
