PURPOSE: To obtain a radiation heating tube, in which the deformation and the crack can be prevented without casting defect and the wt. can be reduced by making the thickness thinner and the temp. control and the heat efficiency in a heating furnace can be improved.

CONSTITUTION: In the radiation heating tube for heating the inner part of the heating furnace with the radiating heat generated while combustion gas (g) flows in the tube body 21 by introducing the combustion gas (g) into the tube body 21 from one end part of the tube body 21 arranged in the heating furnace, the tube body 21 is assembled with one or more of U-shape tube parts 22a-22c and one or more of straight tube parts 13a, 13b, 14a, 14b. The U-shape tube parts 22a-22c are connected with plural tube members 24, 24... by rounding the sheet materials made of a thin heat resistant alloy and butt-welding both end parts under communicating condition, and the straight tube parts 13a, 13b, 14a, 14b are cast tubes made of the heat resistant alloy. By this constitution, the radiation heating tube having easy handling at the time of fitting or at the time of changing, is obtd.