Abstract: A welding jig including a first support member; a second support member; and a pressure adjusting mechanism. Wherein the first support member has a through hole through which a laser beam can pass, the second support member being configured to be insertable into and detachable from a hollow shaft core portion of a jelly roll type electrode assembly, and one end of the second support member supporting an electrode and a bottom of a battery can disposed on a side of one end of the jelly roll type electrode assembly. The pressure adjusting mechanism being configured to adjust a pressure applied between the first support member and the second support member, and the through hole being configured to allow the laser beam to weld the battery can and the electrode.

Abstract: A welding method includes: arranging end portions of a first member and a second member next to each other facing an end surface of the end portions towards a laser device; performing rotational irradiation to the end surface of the end portions of the first member and the second member with laser light at a predetermined rotating diameter, wherein a spot diameter of the laser light is set to be equal to or larger than the rotating diameter, and wherein an irradiation region of the laser light by the rotational irradiation is set to extend over the first member and the second member.