A refrigerator comprising: a cabinet defining a storage space, a first door rotatably mounted on the cabinet, the first door opening or closing the storage space, an opening passing through the first door, a second door mounted rotatable in the same direction as the first door, the second door opening or closing the opening, and an auxiliary shelf of which both sides are shaft-coupled to the opening, the auxiliary shelf contacting a back surface of the second door and being folded or unfolded in a direction crossing the rotation direction of the second door when the second door is opened, wherein the auxiliary shelf comprises: a main plate rotatably mounted on the opening; characterized in that the auxiliary shelf comprises: a sub plate disposed on a front side of the main plate to selectively contact the back surface of the second door; and a connection member connecting the main plate to the sub plate to allow the sub plate to be rotated in the same direction as the auxiliary shelf; wherein front and rear ends of the connection member are rotatably connected to the main plate and the sub plate, respectively; and wherein a damping member connected to a rotation shaft of the main plate to allow the auxiliary shelf to be smoothly unfolded is further disposed on a side of the main plate or the opening. a cabinet defining a storage space, a first door rotatably mounted on the cabinet, the first door opening or closing the storage space, an opening passing through the first door, a second door mounted rotatable in the same direction as the first door, the second door opening or closing the opening, and an auxiliary shelf of which both sides are shaft-coupled to the opening, the auxiliary shelf contacting a back surface of the second door and being folded or unfolded in a direction crossing the rotation direction of the second door when the second door is opened, wherein the auxiliary shelf comprises: a main plate rotatably mounted on the opening; characterized in that the auxiliary shelf comprises: a sub plate disposed on a front side of the main plate to selectively contact the back surface of the second door; and a connection member connecting the main plate to the sub plate to allow the sub plate to be rotated in the same direction as the auxiliary shelf; wherein front and rear ends of the connection member are rotatably connected to the main plate and the sub plate, respectively; and wherein a damping member connected to a rotation shaft of the main plate to allow the auxiliary shelf to be smoothly unfolded is further disposed on a side of the main plate or the opening. a main plate rotatably mounted on the opening; characterized in that the auxiliary shelf comprises: a sub plate disposed on a front side of the main plate to selectively contact the back surface of the second door; and a connection member connecting the main plate to the sub plate to allow the sub plate to be rotated in the same direction as the auxiliary shelf; wherein front and rear ends of the connection member are rotatably connected to the main plate and the sub plate, respectively; and wherein a damping member connected to a rotation shaft of the main plate to allow the auxiliary shelf to be smoothly unfolded is further disposed on a side of the main plate or the opening. a sub plate disposed on a front side of the main plate to selectively contact the back surface of the second door; and a connection member connecting the main plate to the sub plate to allow the sub plate to be rotated in the same direction as the auxiliary shelf; wherein front and rear ends of the connection member are rotatably connected to the main plate and the sub plate, respectively; and wherein a damping member connected to a rotation shaft of the main plate to allow the auxiliary shelf to be smoothly unfolded is further disposed on a side of the main plate or the opening.