Method for insert-molding film material

A film material insert molding method for forming a transparent resin layer on a front surface of a film material having a design portion and a substrate resin layer on a back surface of the film material, the method comprising:

• an intermediate part forming step of forming a first intermediate part having an edge extending radially outward, the edge being disposed at the inside of an outer peripheral end of a final shape of the film material;
• a transparent resin layer forming step of forming a second intermediate part including a transparent resin layer, by injection molding, on a front surface of the first intermediate part, with the edge of the first intermediate part being fixed to a transparent resin layer forming unit;
• and
• a substrate resin layer forming step of forming an insert-molded article including a substrate resin layer, by injection molding, the substrate resin layer covering a back surface of the second intermediate part and a surface of a radially outer end of the edge, so that an end of the film material is prevented from being exposed from an external peripheral side surface of the insert-molded article as a final product.