To bring a slide pin into contact with a protrusion and inject into a core mold to carry out the molding, rotate a core mold plate, move a molded product to a forming position, move the slide pin and inject resin into a cavity to carry out the forming and bond integrally a lens holder with an illuminant holder.

A fitting section A of a molded product 11 is molded by a protrusion 14a, and a step D is molded by a pin 16. Then, a mold is opened and a core template 13 is rotated by 180°, and the molded product 11 is carried to the forming side. In the process, the slide pin 16 is moved by the distance (x), and the step D section of the fitting section A is in the state of being formed in the molded product 11. Black resin is fed from a secondary nozzle N2, passed through a secondary runner R2 and a secondary pin gate G2 and injected into a secondary cavity 14B and formed. Thus the mold is opened, and a final molded product composed of the molded product 11 (lens holder) integrated with the formed product (illuminant holder) 12 is released.