An image forming apparatus which is capable of selecting power states that suit user's intention for a low-power state and a job executable state. A first power-saving state or a second power-saving state in which a smaller amount of power is consumed than in the first power-saving state is set as a power-saving state to which the printing apparatus is shifted when a shifting factor is detected. A first returning method for returning the printing apparatus from the power-saving state when a returning factor that causes the printing apparatus to return from the power-saving state is detected, or a second returning method for returning the printing apparatus from the power-saving state when a function to be used is selected on a function selecting screen displayed in response to detecting the returning factor is set. When the first power-saving state has been set, the first returning method is set.