To amplify the engine torque and suppress the size of a drive device while stepless shifting is conducted with the engine torque divided to a power generator.

A carrier 21C of a first epicyclic gearing mechanism 21 and a sun gear 22S of a second epicyclic gearing mechanism 22 are coupled with the output shaft 1a of an engine 1, while a sun gear 21S of the first mechanism 21 is coupled with a generator 3, and a brake 9 is installed to engage and disengage the ring gears 21R and 22R of the first and second mechanisms 21 and 22 selectively, and the carrier 22C of the second mechanism 22 is coupled with an idler gear 5b, with which a motor 4 is coupled.