An image forming apparatus includes an image forming unit, first and second power terminals both coupled to a power supply, a fixing unit including a heater, a first switch, a first detector, a second switch, and a controller. The first switch includes a triac and is turned on and off on the basis of a first control signal. The first detector generates a first detection signal corresponding to the turning on and off of the first switch. The second switch includes a relay and is turned on and off on the basis of a second control signal. The controller generates the first control signal, and generates, on the basis of the first detection signal, the second control signal. Each of the heater, the first switch, and the second switch is provided in a power supply path that couples the first power terminal and the second terminal to each other.