Abstract: An electric arc welding robot for welding a zone of a rail or the like comprises a movable, electric arc torch unit for operating the welding, first controlling means for controlling a first displacement of the torch unit substantially in front of the periphery of the zone to be welded, so that welding geometrical locations are read on said zone, by means of reading means connected to a memory unit, for memorizing said welding geometrical locations read on the rail, and second controlling means for automatically controlling a second displacement of the torch unit in front of the zone to be welded, within the limits of said reading and as a function of the welding geometrical locations, as memorized.