An electric resistance welding machine in which the welding transformer is rigidly connected to an implement holding head vertically movable on an upper bracket of the machine structure, and therefore it follows the vertical movements of the welding implement so as to reduce the electrical impedance of the circuit. A workpiece-holding table is movably mounted on a lower bracket of the machine and has a lower rib which during welding is clamped by a clamping device for providing electric contact.
