In a welding electrode protecting machine, welding electrodes are protected against a surface treating agent on strips to be welded by applying a proper amount of electrode protecting agent onto surfaces of welding electrodes prior to or during welding operation. A seam welding machine includes a carriage (6) adapted to move in a direction orthogonal to a direction in which strips (1a, 2a) to be welded are fed, a pair of rotatable disk-like welding electrodes (8a, 8b) disposed on the carriage (6) for welding together the strips (1a, 2a) by pressing the strips (1a, 2a) to each other at surface portions thereof along which the strips are to be welded together as the carriage (6) is moved, electrode protecting agent application roll-like members (21a, 21b) for applying an electrode protecting agent (29) onto rotating surfaces of the welding electrodes (8a, 8b) while being in physical contact with the welding electrodes (8a, 8b) under pressure, the electrode protecting agent (29) which is charged from tanks (30a, 30b) by pumps (31a, 31b), and removing roll-like members (25a, 25b) disposed on the carriage for removing the electrode protecting agent (29) remaining on surface portions along which the strips (1a, 2a) to be welded were welded together at a work side relative to the welding electrodes (8a, 8b).