A refrigerator, comprising: a cabinet configured to form a storage space; a first door coupled to a front surface of the cabinet to selectively open and close the storage space, and having an opening formed therein; a case protruding from a rear surface of the first door, and defining an accommodation space at an inside thereof; a second door coupled to a front surface of the first door and configured to selectively open and close the opening of the first door; a first hinge configured to rotatably couple the first door to the cabinet; a second hinge configured to rotatably couple the second door to the first door; and a basket assembly slidably coupled to the first door in a front-to-rear direction of the first door, wherein the basket assembly comprises: a basket received in the accommodation space and configured to accommodate food therein; a first base provided to be slidable in the front direction of the first door by passing through the opening of the first door, the basket being placed on an upper surface of the first base; a second base provided to be slidable in the rear direction of the first door, a third base of which a front end is fixed to a rear surface of the first door, characterized by first base being slidably coupled to an upper surface of the second base; and a rear cover integrally coupled to a rear end of the second base; and wherein the second base is slidably coupled to an upper surface of the third base, wherein, when the second base moves in the rear direction of the first door, the rear cover is configured to open a drawing out hole by moving horizontally together with the second base, and wherein the drawing out hole is formed at a rear surface of the case. a cabinet configured to form a storage space; a first door coupled to a front surface of the cabinet to selectively open and close the storage space, and having an opening formed therein; a case protruding from a rear surface of the first door, and defining an accommodation space at an inside thereof; a second door coupled to a front surface of the first door and configured to selectively open and close the opening of the first door; a first hinge configured to rotatably couple the first door to the cabinet; a second hinge configured to rotatably couple the second door to the first door; and a basket assembly slidably coupled to the first door in a front-to-rear direction of the first door, wherein the basket assembly comprises: a basket received in the accommodation space and configured to accommodate food therein; a first base provided to be slidable in the front direction of the first door by passing through the opening of the first door, the basket being placed on an upper surface of the first base; a second base provided to be slidable in the rear direction of the first door, a third base of which a front end is fixed to a rear surface of the first door, characterized by first base being slidably coupled to an upper surface of the second base; and a rear cover integrally coupled to a rear end of the second base; and wherein the second base is slidably coupled to an upper surface of the third base, wherein, when the second base moves in the rear direction of the first door, the rear cover is configured to open a drawing out hole by moving horizontally together with the second base, and wherein the drawing out hole is formed at a rear surface of the case. a basket received in the accommodation space and configured to accommodate food therein; a first base provided to be slidable in the front direction of the first door by passing through the opening of the first door, the basket being placed on an upper surface of the first base; a second base provided to be slidable in the rear direction of the first door, a third base of which a front end is fixed to a rear surface of the first door, characterized by first base being slidably coupled to an upper surface of the second base; and a rear cover integrally coupled to a rear end of the second base; and wherein the second base is slidably coupled to an upper surface of the third base, wherein, when the second base moves in the rear direction of the first door, the rear cover is configured to open a drawing out hole by moving horizontally together with the second base, and wherein the drawing out hole is formed at a rear surface of the case.