To automatically keep a gas shielded state at an arc generating portion excellent even at a high welding speed in gas shielded arc welding.

An arc welding apparatus comprises a welding speed setting section RC for outputting a welding speed setting signal Sr, shielding gas supply means GB, 7 for supplying shielding gas 6 to a welding torch 4, a flow rate setting section FR for outputting a flow rate setting signal Fr for setting the flow rate of the shielding gas 6 to be supplied to the welding torch 4 by receiving the welding speed setting signal Sr as an input, a flow rate adjusting means FC for adjusting a flow rate of gas so as to correspond to the flow rate setting signal Fr, a pressure setting section PR for outputting a pressure setting signal Pr so as to set the pressure of the shielding gas 6 by receiving the welding speed setting signal Sr as an input, and a pressure adjusting means PC for adjusting pressure of gas so as to correspond to the pressure setting signal Pr.