Laser welding method, laser-welded joint, outside sheathing panel, and body structure for rolling stock

A body structure for rolling stock is disclosed. The body structure may include an outside sheathing of a side construction, and a plurality of reinforcement members joined to said outside sheathing interiorly of said outside sheathing. Each of said plurality of reinforcement members may include a U-shaped part which is substantially U-shaped in cross-section and two fitting flange parts extending continuously from end edges of the U-shaped part in opposite directions. The fitting flange parts may be joined to said outside sheathing by laser welding, and the U-shaped part of at least one of said plurality of reinforcement members may be smaller in width than the U-shaped part of another of said plurality of reinforcement members provided on another part of said outside sheathing.