A non-contact power supply unit including a secondary coil supplies an alternating voltage to multiple heat generation layers provided in a heat generation film. In one of the heat generation layers, a loop is provided as a variable impedance circuit in which the impedance changes according to the frequency. A capacitance element in which the impedance changes according to the frequency is provided in the loop. The heat generation amounts of the heat generation layers are switched by changing the frequency of the alternating voltage generated in the secondary coil according to the size of the recording material that is the heating target.