During a period of a low power state, an image forming apparatus causes a system controller to stop an operation of a second power source and cut off voltage supply from a first power source to each of a power relay, an AC voltage detector, a fixing controller, and a printer controller. At a time of return from the low power state, the system controller starts the power supply from the first power source to each of the power relay, the AC voltage detector, the fixing controller, and the printer controller, and then activates the second power source.