<p>A positioning information transmitter transmits a positioning identifier instead of directly transmitting position information. A positioning information management server stores and manages the positioning identifier and the position information while correlating them with each other. In response to a position information request with a positioning identifier, the positioning information management server converts the positioning identifier into position information according to the aforementioned correlation. Furthermore, the positioning information management server updates the positioning identifier to be transmitted from the positioning information transmitter in a certain time by using predetermined means.</p>
