Underwater laser welding apparatus

PURPOSE: To improve accessibility and operability in a complex structure or a narrow space by locally draining water from a weld zone without the need of a large complicated drying device. CONSTITUTION: In an underwater laser welding equipment by which a welding operation is performed with the irradiation of a laser beam 10 to a work (piping 3) in the water 1, a tapered nozzle 15 extending near a laser spot 14 is formed on the tip end side of a machining head 4, so that a shield gas 24 can be introduced into the nozzle 15, and then, plural lines of grooves 25 are formed spirally around the nozzle opening 28 on the inner circumferential surface of the nozzle 15 so that a swirling force may be imparted to the shield gas 24. The shield gas 24, with a swirling force imparted through the plural lines of grooves, is injected from the tip end of the nozzle 15 and, by this swirling stream of the shield gas 24, the water is efficiently and forcedly drained locally from the area around the weld zone.