In a position detection system that has a plurality of transmitters/receivers placed at least three positions: processing is executed to measure distances among the plurality of transmitters/receivers, each distance being measured a plurality of times, and obtain a minimum value for each distance; processing is executed to obtain an angle between each two adjacent straight lines, each of which is one of straight lines that mutually connect the plurality of transmitters/receivers, by using minimum values, each of which is the minimum value for each distance; and if the absolute value of the difference between 180 degrees and the sum of angles, each of which is the angle between each two adjacent straight lines, inside a triangle formed by straight lines that interconnect three of the plurality of transmitters/receivers is smaller than a predetermined value, processing is executed to take the minimum values as the true values of the distances.