A concavo-convex structure forming layer with a concavo-convex structure on one surface; and a light-reflecting layer on at least part of a surface of the concavo-convex structure. In the optical element, the concavo-convex structure forming layer includes a unit group made up of a plurality of units whose concavo-convex structures are different from each other; each of the units has a flat portion and either a plurality of convexities or a plurality of concavities, with an upper surface of each convexity or a bottom surface of each concavity being substantially parallel to a surface of the flat portion; the convexities or the concavities adjacent to each other have center-to-center distances that are not constant; the convexities or the concavities have a constant height or depth; and in the unit group, units having an identical concavo-convex structure are not arrayed at a pitch of less than 150 μm.