Prismatic battery

A square battery comprising 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 having 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 of the battery can 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 boundary surface and at least a part of the vertical boundary surface being welded by a laser radiated in the vertical direction along the height direction of the side wall portions,
• the battery can has an upper end surface in the lateral direction crossing the height direction of the side wall portions, the upper end surface being provided at the upper end portion of the battery can, an inner wall surface in the vertical direction along the height direction of the side wall portions, the inner wall surface crossing the upper end surface and being provided inside the battery can, and an outer wall surface in the vertical direction along the height direction of the side wall portions, the outer wall surface being provided on the outer side of the battery can, and the upper end surface being formed bridging over the inner wall surface and the outer wall surface, and
• the battery lid has a first opposed surface forming the lateral boundary surface so as to be opposed to the upper end surface of the battery can, and a second opposed surface crossing the first opposed surface and opposed to the inner wall surface of the battery can to form the vertical boundary surface.