A graded optical element is provided that includes graded layers of optical material, wherein the layers may or may not have different indexes of refraction. After forming the trench, a photoresist pattern in which a via hole region is defined is formed by exposure and development processes in a state that a photoresist is thinly coated, in a dual damascene process for first forming the trench than a via hole. An elastic part is formed by bending one side of the flat plate in a length direction of the flat plate so as to be elastically deformable.