An image forming apparatus including an image forming unit to form an image, a user switch unit to output a user operation signal to switch between a power-on state and a power-off state of the image forming apparatus, a main controller to control the image forming unit and to output a power control signal based on the user operation signal, a power switching unit to selectively supply operation power to the main controller based on the user operation signal and the power control signal, and an auxiliary controller to control the power switching unit such that the operation power is not supplied to the main controller when the power control signal is changed in a power-off state.