In a formation method for forming a fine structure in a workpiece (30) containing an etching control component, using an isotropic etching process, a mask (32, 34) having an opening (36) is applied to the workpiece, and the workpiece is etched with an etching solution (38) to thereby form a recess (40), 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.