Each protrusion surface has a shape of a strip extending in an extension direction perpendicular to the arrangement direction. Each protrusion surface tapers toward a top section in a thickness direction of an uneven structure. Each depression surface has a shape of a strip extending in the extension direction. Each depression surface tapers toward a bottom section in the thickness direction of the uneven structure. The protrusion surfaces and the depression surfaces are arranged at a period that limits reflection of light that is incident on the uneven surface in a front-view direction of the uneven surface and diffracts the light incident on the uneven surface to emit diffracted light in an oblique view direction of the uneven surface. The uneven structure has a property of absorbing light incident on the uneven structure.