An area estimation system includes: a radio signal transmitting unit configured to transmit a radio signal to certain radio signal receiving terminal; a radio signal capturing unit configured to capture the radio signal transmitted from the radio signal transmitting unit, to obtain an RSSI for indicating a strength of the captured radio signal; an RSSI receiver unit configured to receive the RSSI, a radio signal transmitting unit ID for uniquely identifying the radio signal transmitting unit, and a radio signal capturing unit ID for uniquely identifying the radio signal capturing unit; an RSSI storage unit configured to store the RSSI, the radio signal transmitting unit ID and the radio signal capturing unit ID in association with one another; and a presence area estimating unit configured to estimate the presence area of the radio signal transmitting unit, by using the RSSI which is obtained by the radio signal capturing unit and stored in the RSSI storage unit.