PURPOSE: To improve the quality and characteristic of a coating film by reducing the temp. gradient in the coating film being dried and stabilizing the physical property of the dried coating film.

CONSTITUTION: A coating material is applied on the surface of a base material in a coating booth 2 to form a coating film. The base material provided with the coating film is introduced into an IR baking and drying furnace 3. The base material is simultaneously irradiated with near-IR and mid-IR in the furnace 3. The base material is irradiated with near-IR and heated to heat the coating film in the thickness region close to the base material, and the intermediate thickness region is heated by the mid-IR. The base material is irradiated simultaneously or alternately with the near-IR and mid-IR.