An auxiliary machine-driving device has a first idler roller disposed between an engine roller and a first rotating roller; a second idler roller disposed between the first rotating roller and a second rotating roller; a third idler roller disposed between the second rotating roller and the engine roller; and a linking mechanism driven by one actuator to switch the first idler roller between a state in which the first idler roller contacts the engine roller and the first rotating roller, and a state in which the first idler roller separates from the engine roller and the first rotating roller, and to switch at least one of the second and third idler rollers between a state in which the at least one roller contacts two rollers adjacent the at least one roller, and a state in which the at least one roller separates from the two rollers.