The optical element includes in order from a light-entering side, a first layer (012), a second layer (013), and a base member (011). The first layer includes a concavo-convex structure with convex portions (012a) and concave portions (012b) alternately formed at a pitch smaller than a wavelength of entering light, and the second layer satisfies the following conditions: where ns represents an effective refractive index of the first layer, nb represents a refractive index of the base member, and nA and dA respectively represent a refractive index and a thickness of the second layer.