An object of the present invention is to provide an anti-reflection film excellent in high-temperature and high-humidity environment resistance and scratch resistance in addition to improved anti-reflection performance of a concave-convex nanostructure. To achieve the object, an anti-reflection film 10 comprises: a base layer 11 as a first optical thin film that is provided on an optical surface 21a of an optical element 21; a concave-convex nanostructure layer that is provided on a surface of the base layer 11 and is composed of a concave-convex nanostructure 12 formed so as to have a pitch width p between the convex parts 12b of shorter than an incident light wavelength; and a cover layer 13 as a second optical thin film that covers peaks of the convex part 12b with a void 14 being provided between the cover layer 13 and concave part 12a constituting the concave-convex nanostructure 12.