The present invention concerns an automatic welding device of MIG/MAG type consisting of at least one carriage holding at least one welding head comprising at least one torch (1) guiding a consumable electrode wire along a parting plane (P) between the pipes to be welded, which brings the current to the end of the electrode wire in order to generate an electric arc and ensure melting of the filler metal,The invention consists of the fact that the welding head therefore presents a welding torch (1) intended to be centered in relation to the parting plane (P) to ensure the penetration pass and also bears at least two other so-called tracking welding torches (2, 3), respectively positioned one after the other following the first so-called central welding torch (1) and offset respectively on both sides of the so-called central torch (1) in order to make lateral passes.Application to the welding of metal pipes in order to form pipelines.