A capacitor, a coil, a flash lamp, and a switching element such as an IGBT are connected in series. A controller outputs a pulse signal to the gate of the switching element. A waveform setter sets the waveform of the pulse signal, based on the contents of input from an input unit. With electrical charge accumulated in the capacitor, a pulse signal is output to the gate of the switching element so that the flash lamp emits light intermittently. A change in the waveform of the pulse signal applied to the switching element will change the waveform of current flowing through the flash lamp and, accordingly, the form of light emission, thereby resulting in a change in the temperature profile for a semiconductor wafer.