To provide a laser welding shield gas for a galvanized sheet iron and a welding method capable of forming an excellent welding processing surface free from adhesion of fumes, and making the welding processing efficient, and decreasing a processing cost.

The shield gas 2 used in welding the galvanized sheet iron M is a mixture of a oxygen gas of 3 vol.% or more and 10 vol.% or less, and a helium gas remainder, and the generation of the fumes is inhibited by making the zinc from the galvanized sheet iron in welding into a zinc oxide Mo by oxidizing the zinc so as not to vaporize the zinc.