PURPOSE: To improve production efficiency by making unnecessary an exchange of a tool or transfer of a rubber product at the time of progress of work from a molding stage to an inspection stage, by a method wherein a molding tool is formed of a nonmetallic conductive material and this one tool serves both as the molding tool and an inspection tool.

CONSTITUTION: A molding tool A constituted of plastic obtained by mixing up with carbon, graphite an conductive powder and nonmetallic conductive material such as ceramics obtained by mixing up with the conductive powder is used. At the time of molding, the tool is immersed into liquid latex rubber and the liquid latex rubber is stuck to its surface. Since a metallic ingredient is not contained basically at the time of formation of a film, the film can be formed uniform and thin. Then the tool is used as the inspection tool as it is and existence of a pin hole is checked electrically through electrification.