A semiconductor wafer held by a susceptor in a chamber is irradiated with halogen light radiated from a plurality of halogen lamps to be heated. A stainless steel block having an opening in a cylindrical shape is provided between the chamber and the halogen lamps. This reduces a distance from a light emitting portion in a light source region in which the plurality of halogen lamps is arranged, throughout the entire circumference of the opening in a cylindrical shape, so that the amount of reflected light from the inner wall surface of the opening toward the peripheral portion of the semiconductor wafer becomes uniform. This causes a uniform increase in illuminance of the peripheral portion of the semiconductor wafer, where temperature tends to decrease, at the time of light irradiation from the halogen lamps, so that in-plane temperature distribution of the semiconductor wafer can be made uniform.