An inverter in which the three-phase power source is used as an input power source and the single phase voltage is outputted, is provided. The single phase output voltage of the inverter is applied onto the inductive coil of the inductive heat generation mechanism provided inside the rotating roller as the exciting voltage. Because the single phase voltage obtained by being phase-converted by the inverter is used, the unbalance is not generated among the phases of the three-phase power source which is the input power source.