The present invention provides an optical member with which degradation of adhesion between a substrate containing triacetylcellulose and a polymer layer caused by moisture absorption is suppressed. An optical member according to the present invention includes a substrate and a polymer layer in direct contact with the substrate and having an indented structure on a surface thereof, the indented structure including multiple protrusions formed at a pitch not greater than a wavelength of visible light. Triacetylcellulose is present in at least a surface of the substrate on the polymer layer side, the polymer layer is formed from a polymerizable composition polymerizable by active energy ray irradiation, and the polymerizable composition contains 30 parts by weight or more and 75 parts by weight or less of a polyfunctional acrylate, 25 parts by weight or more and 60 parts by weight or less of a monofunctional monomer having a tertiary amide group, and 0.1 parts by weight or more and 10 parts by weight or less of a fluorine-containing compound having a reactive group.