Abstract: An automatic arc welding machine of the type which operates with rod electrodes. The electrodes (46), which are held in a welding head (28), are moved automatically with respect to the workpiece. The electrodes are moved longitudinally away from the workpiece in accordance with the arc voltage such that a certain arc length is sustained. After use they are automatically replaced with new electrodes. For this purpose there is provided an arc striking control by means of which the particular electrode (46) is placed on the workpiece with the current limited to a value below the selected welding current; the electrode is then raised from the workpiece by an amount corresponding to the predetermined arc length while the welding current is released, before the longitudinal movement of the electrode in accordance with the arc voltage begins. A precisely timed and accurately placed ignition is achieved in this manner, even if the location of the weld is covered with scale or slag.