An antireflection film includes a plurality of convex structures formed on a light transmission surface included in an optical waveguide. A maximum radial length of a surface that is of each convex structure and that is close to the light transmission surface is less than a minimum value of a visible light wavelength. The maximum radial length of each convex structure gradually decreases in a direction away from the light transmission surface. A height of each convex structure is greater than or equal to 310 nm. A distance between geometric centers of surfaces that are of two adjacent convex structures and that are close to the light transmission surface is less than or equal to 220 nm.