In a formation method for forming a fine structure in a workpiece containing an etching control component, using an isotropic etching process, a mask having an opening is applied to the workpiece, and the workpiece is etched with an etching solution to thereby form a recess, corresponding to a shape of the opening, in a surface of the workpiece. The etching of the workpiece is stopped due to the etching control component eluted out of the workpiece in the etching solution within the recess during the isotropic etching process.