A refrigerator comprising: a cabinet defining a storage space; a door provided in front of the cabinet, the door comprising a main door including an opening and a sub door configured to open or close the opening of the main door; a plurality of shelves provided inside the cabinet; a plurality of shelf guards disposed at the opening of the main door to protrude upward from a front end of each shelf so as to provide a protrusion, the shelf guards being provided to be movable; and a rotation guide device configured to guide a movement of the shelf guards so that, when the sub door is opened, the rotation guide device operates with the opening of the main door to allow the shelf guards to move and extend to a front side of the opening, wherein the rotation guide device comprises: a projection provided at the sub door; a moving part provided at the main door, the moving part being movable by the projection when the sub door closes the opening of the main door, and includes a first rack gear; and characterized in that the rotation guide device further comprises: a first gear assembly configured to allow a first shelf guard of the plurality of shelf guards to rotate and including a first pinion gear interlocked with the first rack gear, and a second pinion gear; a second rack gear interlocked with the second pinion gear and extended in the vertical direction from a side of the opening; and a second gear assembly provided at a height corresponding to a second shelf guard of the plurality of shelf guards to allow the second shelf guard to rotate and interlocked with the second rack gear. a cabinet defining a storage space; a door provided in front of the cabinet, the door comprising a main door including an opening and a sub door configured to open or close the opening of the main door; a plurality of shelves provided inside the cabinet; a plurality of shelf guards disposed at the opening of the main door to protrude upward from a front end of each shelf so as to provide a protrusion, the shelf guards being provided to be movable; and a rotation guide device configured to guide a movement of the shelf guards so that, when the sub door is opened, the rotation guide device operates with the opening of the main door to allow the shelf guards to move and extend to a front side of the opening, wherein the rotation guide device comprises: a projection provided at the sub door; a moving part provided at the main door, the moving part being movable by the projection when the sub door closes the opening of the main door, and includes a first rack gear; and characterized in that the rotation guide device further comprises: a first gear assembly configured to allow a first shelf guard of the plurality of shelf guards to rotate and including a first pinion gear interlocked with the first rack gear, and a second pinion gear; a second rack gear interlocked with the second pinion gear and extended in the vertical direction from a side of the opening; and a second gear assembly provided at a height corresponding to a second shelf guard of the plurality of shelf guards to allow the second shelf guard to rotate and interlocked with the second rack gear. a projection provided at the sub door; a moving part provided at the main door, the moving part being movable by the projection when the sub door closes the opening of the main door, and includes a first rack gear; and characterized in that the rotation guide device further comprises: a first gear assembly configured to allow a first shelf guard of the plurality of shelf guards to rotate and including a first pinion gear interlocked with the first rack gear, and a second pinion gear; a second rack gear interlocked with the second pinion gear and extended in the vertical direction from a side of the opening; and a second gear assembly provided at a height corresponding to a second shelf guard of the plurality of shelf guards to allow the second shelf guard to rotate and interlocked with the second rack gear. a first gear assembly configured to allow a first shelf guard of the plurality of shelf guards to rotate and including a first pinion gear interlocked with the first rack gear, and a second pinion gear; a second rack gear interlocked with the second pinion gear and extended in the vertical direction from a side of the opening; and a second gear assembly provided at a height corresponding to a second shelf guard of the plurality of shelf guards to allow the second shelf guard to rotate and interlocked with the second rack gear.