Abstract: Provided is a digital door lock which can issue a master key, can be operated using a terminal having the master key and can be operated using a terminal having a slave key distributed by a user of the terminal having the master key, regardless of whether the digital door lock is connected to a network. The digital door lock includes: a storage unit which stores a master key unique to the digital door lock and recorded at the time of manufacturing the digital door lock; a wireless communication interface which provides a short-range wireless communication function; and a processor which controls the wireless communication interface to transmit the master key to a master control terminal directly connected through the wireless communication interface.