A cover plate covering a display panel of a display device has a transparent base having a surface facing the display panel and provided with reflection-reducing minute irregularities. The reflection-reducing minute irregularities consist of numerous projections and numerous valleys lying between the projections, and meet a condition expressed by: PMAX≦&lgr;MIN, where PMAX is the maximum distance between the tips of the adjacent projections, and &lgr;MIN is the minimum wavelength in a visible region in a vacuum. The sectional area ratio of total area of sections of the projections of the transparent base in a plane parallel to the transparent base in the plane increases continuously and gradually in a direction from the tips of the projections toward bottoms of the valleys.