To realize a highly efficient driving system making the most of power sources responding to various types of power sources (such as a high-speed/low-torque power like an electric motor and a low-speed/high-torque power like human power) and loads.

In the high-speed/low-torque state, with a magnetic clutch 27, the axial positions of a speed-up gear side transmission plate 41 and a middle disc 46 are energized and positioned by a clutch switching mechanism 47 such that a yoke 40 of the speed-up gear side transmission plate 41 is disposed opposite a magnetic ring 45 of the middle disc 46, which results in the output of the speed-up gear 23 side to be outputted from an output shaft 28 whereas in the low-speed/high-torque state, the direction of thrust generated by the clutch switching mechanism 47 is reversed, so that a yoke 43 of a speed reducer transmission ring 44 is disposed opposite the magnetic ring 45, which results in the output of the speed reducer 25 side to be outputted from the output shaft 28.