PURPOSE: To perform plasma welding of a non-keyhole system at high speed by providing a first opening on a constrained nozzle and providing plural openings surrounding the first opening.

CONSTITUTION: The constrained nozzle 12 of a torch for a plasma arc welding machine is arranged surrounding a nonconsumable type electrode 11 and being insulated from this and the first opening 121 is provided corresponding to the electrode 11. A shielding nozzle 13 is arranged surrounding to constrained nozzle 12 and a second opening 131 is provided surrounding the constrained nozzle 12. Here, the plural openings 122 are provided surrounding the first opening 121 on the constrained nozzle 12. By this method, plasma welding of the non- keyhole system at high speed can be performed.