A fixing device includes: a fixing unit which heats a recording medium to fix a color material adhered to the recording medium; a first heater which heats the fixing unit; a second heater with rated power smaller than the rated power of the first heater which heats the fixing unit; and a controller which performs preliminary control of energizing the second heater when heating of the fixing unit by the first heater is started and energizing control of stepping up power consumption of the first heater and stepping down the power consumption of the second heater such that a change amount when a sum of the power consumption of the first heater and the power consumption of the second heater changes becomes a value to make a flicker value indicating a degree of a flicker not larger than a predetermined standard value after executing the preliminary control.