The present invention provides a double-electrode electric arc welding method which can reduce the dissolved oxygen amount in the welding part. A welding gun which is provided with thread (W) for feeding the welded parent metal (P) and non-consumable electrodes that are collocated to a concentric shape with a mode of surrounding the thread (W) is used for generating GMA electrical arc (6a) between the thread and the welded parent metal (P). Furthermore a plasma arc (6b) is formed between the non-consumable electrode and welded parent metal (P). The central gas (Gc) is supplied with a mode of directly surrounding the GMA electrical arc (6a). The protecting gas (Gs) is supplied to the outside of a concentric shaft for the central gas (Gc) which is an insert gas, and the protecting gas (Gs) is the mixture of insert gas and reducing gas. According to the composition, the oxygen dissolved into the fused bath (Mp) can be eliminated for reducing the dissolved oxygen amount of the welding seam (Wp), thereby increasing the low-temperature flexibility of the welding seam (Wp).