Patent ID: 7831165

Claim:
A fixing device comprising: at least a heating roller, a fixing roller, a heating belt which is stretched over the heating roller and the fixing roller, is heated by the heating roller, and is rotated by a driving unit so as to fix a toner image of a transfer material, and a bias preventing unit of the heating belt provided in the heating roller, wherein: a first mode which is a combination mode of the heating of the heating belt and the rotation stop of the heating belt and a second mode which is a combination mode of the heating of the heating belt and the rotation of the heating belt are set; at the time of returning of the heating belt for an image forming operation from non-heating and non-rotation of the heating belt, the heating belt is controlled by the first mode and the heating belt is then controlled by the second mode transitioned from the first mode; and when a temperature of the heating belt becomes equal to or larger than a mode transition reference temperature which is set on the basis of a predetermined condition, the transition from the first mode to the second mode is performed.