A position detecting system includes an RFID terminal configured to transmit an identification information signal by radio; a plurality of receiving devices configured to receive the identification information signal; and a position detecting server configured to receive a reception notification of the identification information signal from each of the receiving device and configured to estimate a position of the RFID terminal. The RFID terminal includes a part configured to perform radio transmission of a plurality of identification information signals having different radio strengths. The position detecting server includes a part configured to integrate the reception notifications of the identification information signals having different radio strengths and configured to estimate the position of the RFID terminal.