There is provided a novel and improved optical body, master, and method for manufacturing an optical body in which the anti-reflection characteristics are improved even further, and fabrication is facilitated, the optical body having a concave-convex structure in which structures having convex shapes or concave shapes are arrayed on an average cycle less than or equal to visible light wavelengths. The structures have an asymmetric shape with respect to any one plane direction perpendicular to a thickness direction of the optical body. Accordingly, the anti-reflection characteristics are improved even further, and fabrication is facilitated.