PURPOSE: To reduce a construction cost and to maintain rust scattering preventing effect for a long period due to the endurance against the high heat of exhaust smoke by completing the rust scattering preventing treatment of the inner surface of a flue.

CONSTITUTION: A film 2 made of a heat resistant corrosion resistant thin film such as a stainless steel thin film, a ceramic paper or a titanium thin film is disposed along the inner surface 1A of a flue 1 such as an exhaust smoke duct 1a or a stack 1b, and the film 2 is locked to the inner surface 1A of the flue 1.