An MFP (an image forming apparatus) includes a main CPU that performs a predetermined process before switching the MFP to a power supply stop state, in response to a turn-off operation on a main power switch of the MFP, and a sub CPU that controls supply of power to individual units of the MFP in response to a command from the main CPU by a power relay and a power control IC. The sub CPU monitors the operating state of the main CPU after the turn-off operation on the main power switch. After the turn-off operation, even if a power supply stop command from the main CPU is not received, if a predetermined condition related to the result of the monitoring of the operating state of the main CPU is satisfied, the sub CPU performs forced turn-off control for forcibly stopping supply of power to the individual units.