PURPOSE: To perform arc spot welding of good quality by guaranteeing the molten metal quantity in proper quantity in accordance with a gap between an upper work and a lower work even if the gap between the upper and lower works is changed due to a warp, etc., of the works at the time of performing arc spot welding on the lower side work and the upper side work provided with a hole for welding in advance at the hole for welding.

CONSTITUTION: In the method where base metals in the periphery of the hole 11 for welding of the superposed works of the lower side work 2 and the upper side work 1 provided with the hole 11 for welding in advance are molten and the hole 11 for welding is filled up by droplets of a welding wire 33 to perform arc spot welding, the interval between the upper side work 11 and the lower side work 2 and the interval between a tip 31 and the lower side work 2 are measured prior to tip energizing. A welding current and the welding time are set according to the quantities of deviations from reference values of these intervals.