A refrigerator comprises a cabinet having a storage compartment, a main door rotatably coupled to the cabinet and opening and closing the storage compartment, a door opening provided in the main door and in communication with the storage compartment, a sub door opening and closing the door opening, and a basket assembly provided in the door opening and comprising a basket movable forward and backward, wherein the basket assembly comprises a front plate provided under the basket, a front assembly provided under the front plate and configured to move the front plate forward, a rear plate provided under the front rail assembly, and a rear rail assembly provided under the rear plate and configured to move the rear plate backward.