vary from 0 u00b0 to 20 u00b0 from the center of the substrate 85 to the perimeter of the substrate respectively i e the angles of incidence in the region 81 range from 0 u00b0 to 10 u00b0 and the angles of incidence in the region 82 are 10 u00b0 and greater in a single layer pair of this multilayer film the respective thicknesses of the mo layer 86 and the si layer 87 are established such that r varies continuously from 0 45 to 0 35 from the center toward the edge of the region 81 in which the angles of incidence range from 0 u00b0 to 10 u00b0 as in the embodiment of fig3 if u03b3 were to continue to diminish in the region 82 from the edge contacting the region 81 to the edge of the mirror in which the angle of incidence is 10 u00b0 and greater then the reflectivity would decrease as u03b3 drops below 0 35 to prevent such a decrease in reflectivity a conventional compensation scheme in which the thickness of the multilayer film is changed is utilized in the region 82 in other words while maintaining u03b3 0 35 in the region 82 the period length is increased thus according to this embodiment and with respect to mirrors in which a certain area has a broad range of angles of incidence that cannot be compensated for only by varying the distribution of u03b3 a conventional scheme of changing the thickness of the multilayer film i e changing the period length can be applied locally thus the magnitude of change in distribution of film thickness is smaller than when variations of the film thickness distribution were performed in.