PURPOSE: To improve the yield percentage of the molding and simplify the molding device by folding the center of a bulb to be folded so that folded parts of both ends are opposing each other after both parts to be folded on the ends of the bulb are folded to form hook shape separately.

CONSTITUTION: A bulb is entirely heated to degas a phosphor material 2, while exhausting the inside of the bulb, folding part 1c on the exhausting pipe 4 side of second folding parts 1c, 1c' of the bulb is heat-softened, a drum 5 is made to touch the folding part, and nitrogen gas is introduced into the bulb. The other end of the bulb is wound upward along a groove 6 on the drum, and the bulb is molded into hook-shape. Similarly, the second folding part 1c' is molded into reverse hook shape. Then, the center area supposed to be the folding part 1b is made to touch the heat-softening part of the bulb in the direction to normal to the molding direction of the second folding part, and another side 1c' of the second folding part is drawn down to wind the softening part on the drum 5. The folding part 1b is separated from the drum while being cooled.