Means of solution: Optical protrusions 23 of nano-size for restricting reflection of light and protection columns 24 for preventing crushing of the optical protrusions 23 are provided on a surface of a film substrate 22. The protection columns 24 have a frustum shape. When a ratio of a projection area in which all of lateral surfaces of a single protection column 24 are projected on a surface of the film substrate 22 from a direction that is perpendicular to the surface of the film substrate 22 to a divided area on the surface of the film substrate 22 with respect to the single protection column 24 is defined to be a lateral surface projection occupying area rate, the lateral surface projection occupying area rate of the antireflection film is not more than 0.25% and not less than 0.01%.