PURPOSE: A security system is provided to reduce robberies by using double information by additionally asking designated information for opening a door of an owner. CONSTITUTION: A security system(10) asks information(24) of a device(20). The security system opens a door by providing the information to the device. The security system is additionally connected to a system in a real time inquiry business by communication. The security system inquires locations to the device in real time while the information is supplied to the device. The security system stores user information and the information asked from a designated device of an owner. The security system is connected to a monitor unit and the system in the real time inquiry business. The security system inquires positions of the device in real time.
