To keep a color loss area of a tubular bulb inside the area covered by a base.

The base 5 is mounted as covering the base end part of a straight pipe part 7, an exhaust pipe 9, and a tubular bulb main unit 6. The exhaust pipe 9 is extended by nearing a sealed end 9a to the outer surface of the base 5, a stem main unit 8 is formed by having an extended base end part 8a which makes the sealed end 9a protrude, the straight pipe part 7 forms an extended straight pipe 7a by extending an opening end 7b, and the extended straight pipe part 7a is welded to the extended base end part 8a of the stem main unit 8. The welding area M between a tubular bulb part 2 and a stem part 4 is placed between each extended straight pipe part 7a and the extended base end part 8a, they are away from the tubular bulb main unit 6 so that the area A of color loss caused by electric heat upon welding can be kept in the area covered by the base 5.