According to an embodiment, an image forming apparatus includes: a motor that drives a fixing device; and a controller. The motor outputs a signal corresponding to a driving current value of the motor. The controller performs a first operation where a magnitude value of the signal has fallen out of a first range while driving the motor in a first operation mode. The controller performs a second operation where the magnitude value of the signal has fallen out of a second range while driving the motor in a second operation mode.