A mask frame includes a frame and a mask installed on the frame while being stretched in a first direction. The mask includes a deposition area including a plurality of deposition pattern portions, an edge unit formed to have a thickness greater than a thickness of the deposition area and including a first edge and a second edge that extend in the first direction on two sides of the deposition area, and two or more ribs formed to have a thickness greater than the thickness of the deposition area between deposition pattern portions adjacent to each other in a second direction perpendicular to the first direction.