A radiant tubes support device, which can be used in furnaces for the thermal treatment, for continuous lines for galvanising and annealing strips or panels made of metal sheet or other products made of steel or other metals, including a furnace side wall support, constrained to a wall of the furnace, a radiant tube support provided with a tubular element and anti-sticking means between the tubular element and the furnace side wall support for supporting the radiant tube and allowing the lateral oscillation thereof, avoiding the sticking on the furnace side wall support.