A fixing device includes a pair of rotating members and a heating part. The pair of rotating members holds a recording medium, passes the recording medium and thermally fixes toner on the recording medium. The heating part heats one rotating member of the pair of rotating members to increases a temperature of the rotating member. The heating part is PID or PI controlled. When power consumption of an apparatus including the pair of rotating members is not higher than a predetermined value, a PID coefficient or a PI coefficient used in the PID control or the PI control is set to be smaller than when the power consumption is higher than the predetermined value.