Access points are grouped into access point groups. An access point group table that stores correlation between the access point groups and the access points and a terminal position table that manages the correlation between the access point groups and a terminal are provided for a position managing server that manages the position of the terminal. An access point notifies the position managing server of the identifier of the access point itself and the identifier of the terminal being connected to the access point. In the position managing server, an access point group to which the access point belongs is found by searching the access point group table. The terminal is registered in the column of “access point group” of the terminal position table.