Location service providing system and method for providing triggered location request service

A location information service system for supplying a triggered location request service and a method are provided to calculate a location of a target terminal according to a location calculation method selected by the target terminal, for a location service of the target terminal to be provided even when location calculation continuously is impossible with the currently set location calculation method. An H-SLP(Home-SUPL(Secure User Plane Location) Location Platform) server receives information on location calculation methods supportable by a target terminal(302) from the target terminal(302), sets priority of the methods to send the set priority to the terminal(302), and uses one method to provide a location service in accordance with a triggered location request service if information on the particular location calculation method is received from the terminal(302). If a condition in accordance with the triggered location request service is satisfied, the terminal(302) selects one of the methods suitable for the current propagation environment, sends information on the selected method to the server, and uses the method to provide the location service in accordance with the triggered location request service.