A security system using home gateway alliance includes an alliance management server which includes a gateway registration unit which registers at least one of position information and IP (Internet Protocol) information of a home gateway upon making a request for registration of the home gateway; and an alliance management unit which, in response to a request for alliance from a user terminal of the home gateway registered with the gateway registration unit, sets an alliance relationship between the home gateway having made the request for alliance and other home gateways adjacent to the home gateway having made the request for alliance.