The front surface of a semiconductor wafer with a back surface supported by lift pins is irradiated with a flash of light from flash lamps, so that the semiconductor wafer is heated. A transparent restriction ring made of quartz is into abutment with or close to a peripheral portion of the front surface of the semiconductor wafer. In this state, the flash irradiation is performed. If the temperature of the front surface of the semiconductor wafer rises rapidly when the flash irradiation is performed, the restriction ring restrains the semiconductor wafer from jumping up from the lift pins. This prevents wafer cracking resulting from the jumping of the semiconductor wafer when the flash irradiation is performed.