Abstract: A magnetic seam tracking device designed to orientate the feed or forward motion of a soldering tool along the edges of metal sheets disposed head against head and to be submitted to the soldering operaion. The device comprises a carriage or truck B capable of retaining the soldering tool A, said carriage or truck being provided with track-chains (30), the articulated elements whereof have permanent magnets (40-42) which co-operate with metal sheets (D1) and (D2) to be soldered.