An optical device is provided and includes a substrate having a three-dimensionally random concave-convex shape on the surface thereof, and a hard coat layer formed on the substrate, wherein a projection height with the maximum frequency on the substrate surface falls within the range of 1.5 [mu]m or more and not more than 10 [mu]m. Projections larger than the projection height with the maximum frequency on the substrate surface have a height falling within +3 [mu]m from a central value of the projection height with the maximum frequency. A length RSm in a lateral direction of concaves and convexes on the substrate surface is 55 [mu]m or more and not more than 500 [mu]m.