A network-initiated area event triggered positioning method for a terminal in a session-based position information system is discussed. Network-initiation of area-based positioning of a roaming terminal is discriminated according to a proxy mode and a non-proxy mode, and area-based positioning for the roaming terminal is performed in various manners according to whether an SLP for performing the positioning procedure with respect to the discriminated modes is a V-SLP or an H-SLP.