A process for producing a welded joint, comprising the steps of: preparing a base material wherein the base material is a martensitic stainless steel consisting of, by mass%, C: 0.001 to 0.100%, Si: 0.050 to 1.00%, Mn: 0.10 to 1.50%, P: not more than 0.040%, S: not more than 0.0100%, Cu: 0.01 to 2.00%, Cr: 10.50 to 14.00%, Ni: 0.50 to 10.00%, N: not more than 0.1%, sol. Al: not more than 0.040%, at least one of Mo: 0.10 to 4.00% and W: 0.20 to 6.00%, and the balance being Fe and impurities or wherein the base material is a duplex stainless steel consisting of, by mass%, C: not more than 0.03%, Si: 0.20 to 1.00%, Mn: not more than 8.00%, P: not more than 0.040%, S: not more than 0.0100%, Cu: 0.20 to 4.00%, Cr: 20.0 to 30.0%, Ni: 4.00 to 8.00%, N: 0.100 to 0.350%, sol. Al: not more than 0.040%, at least one of Mo: 0.50 to 4.00% and W: 0.01 to 4.00%, optionally V: not more than 1.50%, optionally Ca: not more than 0.0200%, optionally Mg: not more than 0.0200%, optionally B: not more than 0.0200%, optionally rare earth metals: not more than 0.2000%, and the balance being Fe and impurities; and subjecting the base material to GMA (Gas Metal Arc) welding using a shielding gas comprising 1 to 2 volume% or 35 to 50 volume% of CO 2, and the balance being inert gas, thereby forming a weld metal consisting of, by mass%, C: not more than 0.080%, Si: 0.20 to 1.00%, Mn: not more than 8.00%, P: not more than 0.040%, S: not more than 0.0100%, Cu: not more than 2.0%, Cr: 20.0 to 30.0%, Ni: 7.00 to 12.00%, N: 0.100 to 0.350%, O (oxygen): 0.02 to 0.14%, sol. Al: not more than 0.040%, at least one of Mo: 1.00 to 4.00% and W: 1.00 to 4.00%, and the balance being Fe and impurities. preparing a base material wherein the base material is a martensitic stainless steel consisting of, by mass%, C: 0.001 to 0.100%, Si: 0.050 to 1.00%, Mn: 0.10 to 1.50%, P: not more than 0.040%, S: not more than 0.0100%, Cu: 0.01 to 2.00%, Cr: 10.50 to 14.00%, Ni: 0.50 to 10.00%, N: not more than 0.1%, sol. Al: not more than 0.040%, at least one of Mo: 0.10 to 4.00% and W: 0.20 to 6.00%, and the balance being Fe and impurities or wherein the base material is a duplex stainless steel consisting of, by mass%, C: not more than 0.03%, Si: 0.20 to 1.00%, Mn: not more than 8.00%, P: not more than 0.040%, S: not more than 0.0100%, Cu: 0.20 to 4.00%, Cr: 20.0 to 30.0%, Ni: 4.00 to 8.00%, N: 0.100 to 0.350%, sol. Al: not more than 0.040%, at least one of Mo: 0.50 to 4.00% and W: 0.01 to 4.00%, optionally V: not more than 1.50%, optionally Ca: not more than 0.0200%, optionally Mg: not more than 0.0200%, optionally B: not more than 0.0200%, optionally rare earth metals: not more than 0.2000%, and the balance being Fe and impurities; and subjecting the base material to GMA (Gas Metal Arc) welding using a shielding gas comprising 1 to 2 volume% or 35 to 50 volume% of CO 2, and the balance being inert gas, thereby forming a weld metal consisting of, by mass%, C: not more than 0.080%, Si: 0.20 to 1.00%, Mn: not more than 8.00%, P: not more than 0.040%, S: not more than 0.0100%, Cu: not more than 2.0%, Cr: 20.0 to 30.0%, Ni: 7.00 to 12.00%, N: 0.100 to 0.350%, O (oxygen): 0.02 to 0.14%, sol. Al: not more than 0.040%, at least one of Mo: 1.00 to 4.00% and W: 1.00 to 4.00%, and the balance being Fe and impurities.