A process for fabricating a mold for an aspherical microlens having a desired aspherical and smooth surface, the lens having an effective diameter of 1 mm or smaller and a thickness of 0.5 mm or greater. A double-layer mask layer is formed on a single crystal silicon substrate, and anisotropic etching and isotropic etching are carried out using a first mask layer so as to form a concave portion that is a little smaller than the size of a desired microlens mold. Isotropic etching is then carried out using a second mask layer so as to enlarge the concave portion, thereby obtaining a microlens mold having desired dimensions.