An optical element has a plurality of first machining portions and a plurality of second machining portions. The plurality of first machining portions is aligned in a first direction and the first machining portions each have a convex shape. The plurality of second machining portions is aligned in the first direction along the plurality of first machining portions and the second machining portions each have a convex shape. Ends of the second machining portions in the first direction are adjacent to the corresponding first machining portions, in a second direction perpendicular to the first direction. The ends of the second machining portions in the first direction are disposed further from end of the corresponding first machining portions in the first direction, than the length of the first machining portions or the second machining portions in the second direction.