PURPOSE: To efficiently perform the smoking of a material to be treated at stable high intermaterial temp. by forming an exhaust gas barrier plate opened to the upper part of a material wood smoking treatment chamber along the inner side wall of the treatment chamber.

CONSTITUTION: An exhaust gas barrier plate 9 having a horizontal U-shape cross section is formed to the inner side wall 35 of a treatment chamber. The barrier plate 19 has an opening at the upper part thereof as the inlet 16 of an exhaust cylinder. The exhaust cylinder 9 and explosion-proof valve communicating with the exhaust cylinder formed by the barrier plate 16 are provided to the outside of the side wall 3 and a fan 10 is provided in the exhaust cylinder 9. By positioning the inlet 16 of the exhaust cylinder to the upper part of the side wall 35, the treatment chamber is filled with a larger quantity of exhaust gas and the intermaterial temp. of the material to be treated is not affected by the outlet temp. of a flue and can be set to relatively stable high temp. The intermaterial temp. is pref. about 35-50°.