The present invention provides a method of making a mold for manufacturing a microlens having a smooth surface and an arbitrary aspherical surface, or more specifically, an aspheric microlens of dimensions such that an aperture is equal to or less than 1 mm and a thickness is equal to or more than 0.5 mm. A mask layer having plural circular apertures with different sizes formed therein for a mold for one lens is formed on a silicon substrate. Plural holes are formed for the lens in the silicon substrate by applying anisotropic dry etching to a surface to be processed, which is the surface having the mask layer formed thereon. The depths of the respective holes vary depending on the sizes of the circular apertures. Isotropic etching is performed to remove sidewalls of the plural holes with different depths formed in the silicon substrate, thereby merging the holes into one hole corresponding to the lens.