Abstract: To provide a gradation mask which can easily assure distribution of desired exposure intensity.?Means to accomplish the object!A metal and/or metallic compound film 2 (FIG. 1) is uniformly formed on a transparent substrate 1 such that they have a transmittance of 10% or less. An etching mask having a desired pattern is formed on the metal and/or metallic compound film 2. The metal and/or metallic compound film 2 is dry- or wet-etched. The metal and/or metallic compound film 2 is repeatedly subject to patterning and etching steps by using etching masks with different patterns, so that the obtained layers have a thickness Z(X, Y) varying in three or more steps in accordance with desired transmittance.

Abstract: A two-dimensional shape of a dotted pattern and optical densities of dots or sizes of dots having the same optical density are calculated as write data on the basis of a target distribution of transmittance. The dotted pattern is optically written on a photosensitive medium in accordance with the calculated write data, using a beam from a light source whose output is stepwise or sequentially variable. A latent dotted pattern on the photosensitive medium is developed, thereby obtaining an exposure mask having a desired two-dimensional distribution of transmittance expressed by the dotted pattern and the optical densities of dots or the sizes of dots having the same optical density.