PURPOSE: To provide a radiant tube capable of effectively utilizing the majority or a neat quantity radiated from the surfaces of heating faces for the heating of an object to be heated.

CONSTITUTION: A tube main body 1 of a radiant tube is made to have a sectional shape wherein a radiant area of heating faces 2 facing an object to be heated becomes larger than that of a non-heating face 3 which does not face the object to be heated. Also, by applying coating to the tube main body 1, emissivity on the surfaces of the heating faces 2 is made greater than that on the surface of the non-heating face 3.