PURPOSE: To make a container thin-type and light-weighing by a method wherein a thin plate for sealing is fixed in advance to a glass container, further a thin plate provided with a hole is placed on the thin plate for sealing for being welded, further a back metal is placed on the thin plate provided with the hole for being welded and sealed.

CONSTITUTION: A hole 33 is provided on a thin plate 32 for sealing fixed in advance to a glass container 30 with frit 31 or the like in the position further inside of an inner wall of the container 30, a thin plate 35, whose outer diameter size is reduced than that of the thin plate 32 and whose outer circumferential end face on the opposite side to the part contacting with the thin plate 32 is provided with an outwardly tapered part 34, is placed, and the tapered part 34 is irradiated with a laser for performing seam welding. Next, a back metal 36, whose outer diameter size is reduced than the thin plate 35 and whose outer circumferential end face on the opposite side to the part contacting with the thin plate 35 is outwardly tapered 38, is placed and the tapered part 38 is irradiated with a laser to be seam-welded for performing sealing. Thereby, the container 30 can be made thin-type and light weighing.