To obtain a small-sized precision molded article which can satisfy both precision and a channel shape and can obtain a high dimensional precision without generating cracking and deformation.

In manufacturing a mold for molding the small-sized precision molded article by using a thermosetting resin material, a method for processing the mold by etching is provided, and an ejector pin is installed on the periphery of the outside of a cavity, and when the molded article is separated from the mold, a resin part is ejected by the ejector pin.