A fixing device includes an excitation coil, a fixing member heated by electromagnetic induction by the excitation coil, a magnetic shunt alloy member, a Curie temperature of which is higher than a target fixing temperature, a determiner that determines whether the temperature of a non-sheet passing region of the fixing member is about to reach the Curie temperature, and a power controller that controls power supplied to the excitation coil. Until the determiner determines that the Curie temperature is about to be reached, the power controller performs feedback control to provide power to the excitation coil. When the determiner determines that the Curie temperature is about to be reached, the power controller switches to fixed power control so that a difference between power supplied when the Curie temperature is about to be reached and power supplied after reaching the Curie temperature falls within an allowable range.