According to one embodiment, an image forming apparatus includes a fixing roller, a heater, a heater controller, and a roller controller. The fixing roller conveys a sheet by rotation and fixes a recording material formed on the sheet to the sheet. The heater heats the fixing roller. The heater controller controls a temperature of the heater. The roller controller controls a rotation speed of the fixing roller. When the roller controller satisfies a predetermined condition indicating that a fixing part temperature indicating a temperature of the fixing roller is not suitable for operation, the roller controller increases a rotation speed to be higher than a rotation speed of a case in which the predetermined condition is not satisfied.