A refrigerator comprising a cabinet defining a first storage compartment in which a food is stored, a main door rotatably mounted on the cabinet to open or close the first storage compartment and having an opening; a door hinge connecting an upper end of the main door to a top surface of the cabinet; a separate hinge disposed on a lower end of the main door to rotatably mount the main door to the cabinet; an accommodation device that is accessible through the opening of the main door, the accommodation device defining a second storage compartment in a back surface of the main door, a sub door opening or closing the opening; an upper hinge rotatably mounting the sub door on the main door, the upper hinge having one end coupled to the upper end of the main door and the other end coupled to a top surface of the sub door; a lower hinge disposed on a lower end of the sub door and mounted on the main door to rotatably support the sub door; a cap deco coupled to a lower end of the sub door; and a door opening assembly (400,500) configured to restrict the sub door to main door or release the restriction of the sub door from the main door, characterized in that the main door further includes a receiving part defined in one side of the main door, wherein the door opening assembly (400, 500) includes: a locking member (430,531) rotatably disposed in the sub door at a position corresponding to the receiving part and protruding from a back surface of the sub door, the locking member configured to be selectively received in the receiving part by rotating, in order to restrict the sub door to the main door or release the restriction of the sub door from the main door; a manipulation member (410,511) disposed on a corner of the lower end of the sub door, a portion of the manipulation member (410,511) being exposed outside the cap deco; and a connection member (420,521) disposed inside the sub door, having a lower end connected to the manipulation member (410,511) and an upper end connected to the locking member (430,531), wherein the connection member (420,521) is configured to move up and down by an operation of the manipulation member (410,511) to rotate the locking member (430,531) to release the restriction of the sub door from the main door. a locking member (430,531) rotatably disposed in the sub door at a position corresponding to the receiving part and protruding from a back surface of the sub door, the locking member configured to be selectively received in the receiving part by rotating, in order to restrict the sub door to the main door or release the restriction of the sub door from the main door; a manipulation member (410,511) disposed on a corner of the lower end of the sub door, a portion of the manipulation member (410,511) being exposed outside the cap deco; and a connection member (420,521) disposed inside the sub door, having a lower end connected to the manipulation member (410,511) and an upper end connected to the locking member (430,531), wherein the connection member (420,521) is configured to move up and down by an operation of the manipulation member (410,511) to rotate the locking member (430,531) to release the restriction of the sub door from the main door.