A refrigerator includes a cabinet defining a storage chamber, a drawer door inserted into and withdrawn out of the storage chamber, a motor assembly provided at the storage chamber, a rack gear assembly provided at the drawer door and having an extendable rack gear that is configured to be coupled to the pinion gear, and a guide unit that is provided at an inner surface of the storage chamber and configured, based on the drawer door being withdrawn out of the storage chamber, to couple a portion of the rack gear assembly to the inner surface of the storage chamber to thereby allow the rack gear to extend. The drawer door includes a drawer part that defines an upwardly open storage space, and a door part that is configured to, based on the drawer door being inserted into the storage chamber, close the storage chamber.