A position detection system includes a measurement unit that obtains a measurement value related to transmission and reception of radio waves from when the radio waves are transmitted from one of first and second communication devices to the other one of the first and second communication devices to when the one of the first and second communication devices receives a response to the radio waves to detect a positional relationship of the first and second communication devices. The measurement unit obtains multiple measurement values by performing communication to obtain the measurement value a multiple number of times in which a parameter of the communication is changed.