A power supply circuit receives power from a power supply and supplies the power to loads including a main controller and a first sub-controller performing response action through a network when the supply of power to the main controller is blocked and the image forming apparatus is connected to the network. A second sub-controller controls the blocking of the supply of power to the main controller. The sub-controller determines whether to block the supply of power to the main controller, determines a connection state of the image forming apparatus to the network when the first determination unit determines to block the supply of power, blocks the supply of power to the first sub-control unit according to the determination result, and detects a factor for resuming the supply of power to the main controller and a factor for blocking the supply of power to all or a part of the loads.