A position detection system includes a capsule medical device having therein a magnetic field generator configured to generate a magnetic field, magnetic field detectors configured to detect the magnetic field and output detection signals, and a processor including hardware. The processor is configured to: calculate a position of the capsule medical device by using at least one of the detection signals determine whether the position of the capsule medical device falls within a predefined detection target region for the capsule medical device determine whether proper position detection for the capsule medical device based on the detection signals is possible and set a threshold to be used for determining whether the proper position detection for the capsule medical device is possible, based on the position of the capsule medical device if the position of the capsule medical device falls within the predefined detection target region for the capsule medical device.
