An image forming apparatus includes a fuser unit configured to make an image fused to a recording medium, a selecting unit configured to select a duplex scanning mode or a single-side scanning mode, a check unit configured to determine which one of the duplex scanning mode and the single-side scanning mode is selected, a duplex scanning unit configured to perform a scan when both sides of a document sheet are scanned upon the duplex scanning mode being selected, a setting unit configured to determine power supplied to the fuser unit upon determining, by the check unit, that the single-side scanning mode is selected, and a supply unit configured to supply the determined power to the fuser unit, wherein the determined power is equal to a sum of power consumed by the duplex scanning unit and power that is consumed by the fuser unit upon the duplex scanning mode being selected.