A surface of a semiconductor wafer with a gate of a high dielectric constant film formed thereon is heated to a target temperature for a short time by irradiating the surface with a flash of light. This promotes the crystallization of the high dielectric constant film while suppressing the growth of an underlying silicon dioxide film. Subsequently, the temperature of the semiconductor wafer subjected to the flash heating is maintained at an annealing temperature by irradiating the semiconductor wafer with light from halogen lamps. An annealing process after the flash heating is performed in an atmosphere of a gas mixture of hydrogen gas and nitrogen gas. The annealing process is performed on the semiconductor wafer in the atmosphere of the hydrogen-nitrogen gas mixture, so that defects present near the interfaces of the high dielectric constant film are eliminated by hydrogen termination.