Welding apparatus and method for manufacturing power storage device

A welding apparatus configured to weld a case body and sealing plate of a power storage device to each other, the case body having an opening, the sealing plate attached to the opening, the welding apparatus comprising:

• a workpiece disposition unit on which an assembly of the case body and the sealing plate is disposed with the opening facing upward with the sealing plate attached;
• a laser irradiation device disposed above the workpiece disposition unit;
• and
• an inert gas supply device, wherein
• the inert gas supply device comprises a nozzle at a position that is lower than an upper end of the case body of the assembly disposed on the workpiece disposition unit, and
• the nozzle has an outlet port configured to blow inert gas toward a boundary between the case body and the sealing plate from a position lower than the upper end of the case body within the assembly, with respect to the assembly disposed on the workpiece disposition unit.