PURPOSE: To obtain a shade different in shape or a shade having a thin plate shaped flange not falling even if an ornament is attached by the same mold.

CONSTITUTION: A plate-shaped plasticized methyl methacrylate(MMA) resin 5 is placed on a stand 1 at a predetermined position and air is blown against the rear surface of the MMA resin 5 from an air blow port 1a. Whereon the MMA resin 5 is expanded to be uniformly pressed to the inner wall surfaces of respective split molds 2, 3, 4. However, since a gap 24 is provided between the split molds 2, 3 and the split mold 4, the MMA resin 5 enters the gap 24 to become an outwardly expanded shape. Next, the split mold 4 is allowed to fall to a predetermined position before the plasticized MMA resin 5 is perfectly solidified to press the swelling entering the gap 24 to form a plate-shaped flange having predetermined thickness.