The method of the present invention comprises a first blasting step wherein the surface of a metallic base material for a shower head and treatment container, etc., is blast-treated using a blasting material made from a non-sublimating material (e.g., alumina), and a second blasting step wherein the surface of the aforementioned metallic base material blast-treated in the aforementioned first step is blast-treated using a blasting material made from a sublimating material (e.g., dry ice). The surface of the metallic base material is suitably roughened by means of the first blasting step so that an adhered thin film produced by film formation processing will not be susceptible to peeling, thus preventing the production of particles derived from the adhered thin film, and any residue of non-sublimating blasting material adhered to the surface of the metallic base material is almost certainly removed by the second blasting step, preventing the production of particles derived from non-sublimating blasting material residue falling from the metallic base material.