In a position calculating method performed by a system including beacons, and a control device capable of communicating with the beacons: at least one of the plurality of beacons receives, from a terminal present in the radio wave reaching distance of the beacon, a first signal including terminal identification information identifying the terminal, measures the reception strength of the received signal, and transmits a second signal which includes the terminal identification information, the reception strength and beacon identification information identifying the beacon; and the control device receives the second signal from one of the plurality of beacons, and, on the basis of the position information of the beacon corresponding to the beacon identification information included in the second signal, and on the basis of the reception strength included in the second signal, calculates the position of the terminal corresponding to the terminal identification information included in the second signal.