PURPOSE: To enhance the plasma-resistant property and the heat-resistant property of a resist mask by a method wherein the treatment ability of a hardening apparatus is not reduced and only the surface of a resist film is not hardened earlier.

CONSTITUTION: 1) The title apparatus is provided with the following: a treatment chamber 4 in which a wafer 5 to which a photoresist film has been applied is placed inside and which can be evacuated; light sources 1 by means of which the surface of the wafer is irradiated with ultraviolet rays; louvers 2 which are installed between the light sources and the wafer and which can ne opened and shut; and a louver drive part 3 which arbitrarily changes the opening and shutting angle of the louvers. 2) Resin materials which absorb the ultraviolet rays are pasted on the surface facing the light sources of the louvers. 3) The title apparatus is constituted so as to be provided with a monitor which measures the intensity of irradiation of the ultraviolet rays on the surface of the wafer.