In a sheet-fed printing press including; an impression cylinder gear driven by an upstream drive motor of an upstream printing unit group; an impression cylinder rotationally driven by the impression cylinder gear; a transfer cylinder gear of a convertible press mechanism rotationally driven by the upstream drive motor through the impression cylinder; and a transfer cylinder which is provided with a notch and is rotationally driven by the transfer cylinder gear, a load motor is provided to the transfer cylinder or the transfer cylinder gear, and braking force of the load motor is controlled according to load on the upstream drive motor.