Abstract: A square battery includes a battery can surrounded by four side wall portions, and having an upper end portion on one side in a height direction of the side wall portions opened and a bottom portion in a lower end portion on the other side in the height direction, and a battery lid welded to the upper end portion to seal the battery can, wherein between the battery can and the battery lid, a lateral boundary surface in a lateral direction crossing the height direction of the side wall portions and a vertical boundary surface in a vertical direction crossing the lateral boundary surface and along the height direction of the side wall portions are formed, at least a part of the lateral and vertical boundary surfaces being welded by a laser radiated in the vertical direction along the height direction of the side wall portions.

Abstract: A square battery includes a battery can surrounded by four side wall portions, and having an upper end portion on one side in a height direction of the side wall portions opened and a bottom portion in a lower end portion on the other side in the height direction, and a battery lid welded to the upper end portion to seal the battery can, wherein between the battery can and the battery lid, a lateral boundary surface in a lateral direction crossing the height direction of the side wall portions and a vertical boundary surface in a vertical direction crossing the lateral boundary surface and along the height direction of the side wall portions are formed, at least a part of the lateral and vertical boundary surfaces being welded by a laser radiated in the vertical direction along the height direction of the side wall portions.

Abstract: A hybrid welding method of laser welding and arc welding for a T-joint in which a rib as one member to be welded abuts orthogonally onto a surface of a flange as other member to be welded includes forming a groove portion on a lateral surface of the rib that is an abutting part between the rib and the flange forming the T-joint; forming a flat part at a bottom part of the groove portion formed in the abutting part between the rib and the flange; and performing a hybrid welding using both laser welding in which the groove portion A with this flat part therein is irradiated with a laser beam, and arc welding, to form weld beads of weld metal in the groove portion A, so that welding together the flange and the rib forming the T-joint.