Abstract: Provided is a door lock. The door lock includes a door lock body installed on a door and having an opening/closing device; a memory to store a door lock identifier including a door recognition code and a door lock ID corresponding to the door recognition code; an antenna to sequentially receive a first RF signal and a second RF signal from a reader; and a control unit configured to transmit the door recognition code to the reader and configured to determine whether the door lock ID provided from the door lock management server through the reader matches the previously assigned door lock ID of the door lock identifier to control the opening/closing device.