To enhance welding performance by enabling arc rigidity such as arc expansion and arc softness being set to a desired state by continuously changing a current wave form, in TIG (tungsten inert gas) welding using a welding current Iw varying in a sine curve with a predetermined cycle T and a predetermined amplitude (Ip-Ib).

The invented TIG welding current control method comprises the steps of setting the steep variation width ΔI of the current in advance in order to set the arc rigidity to a desired value and applying, repeatedly in every cycle T, the welding current Iw changing Iw steeply by the steep variation width ΔI of the current at the initiating point tl of the cycle T, the point t2 of half the cycle (T/2) and the terminating point t3 of the cycle T and changing approximately in the sine curve during the period other than those.