An apparatus for welding together two metal sheets (4, 5) includes clamping rails (17, 18; 23, 24) for positionally fixing the sheets (4, 5) each on a table (2, 3), and an induction device movable towards and away from a joint (15) between the metal sheets (4, 5) and along the direction (16) for heating the metal sheets (4, 5) in the joint region (1 5). The induction device displays a first conductor which extends along and adjacent the joint (15). The clamping rails (17, 18; 23, 24) are disposed two (17, 23) at the one sheet (5), and two (18, 24) at the other sheet (4), one on either side of each respective sheet, and along and a slight distance away from the joint (15). The clamping rails (17, 18; 23, 24) are disposed without electric conducting connection with the first conductor, are manufactured from electrically conductive material, and are electrically connected to the sheets (4, 5).