Abstract: A digital door lock system includes a server adapted for managing reservation information and settlement information of guest rooms in a lodging establishment and information on digital door lock passwords in the lodging establishment; a user terminal communicating with the server to perform a reservation and a settlement of a guest room, transmit a digital door lock password directly set by a user to the server; and a door lock device adapted for receiving a digital door lock password from the server to store it and for opening and closing the digital door lock depending on whether the stored digital door lock password is matched with a password inputted by the user. The digital door lock system and a control method thereof allow the user to check in at a desired time and a provider for the establishment to cut down personnel expenses.