There is provided a positioning system which generates an appropriate response according to a positioning accuracy request class from a client device. A client device 101 specifies the positioning accuracy and the request class thereof that it requests to transmit a positioning request of a mobile station 103 to a server device 102. The server device 102 checks the positioning accuracy requested by the client device 101, and, if positioning results which satisfy the requested accuracy exist, responds the positioning results. If the positioning results which satisfy the requested accuracy do not exist, the server device 102 checks the accuracy request class, selects the positioning results with the highest positioning accuracy to respond to the client device 101 in the case of a second class (“Best Effort”), and notifies an error to the client device 101 in the case of a first class (“Assured”).