To improve travel performance in engine drive while miniaturization of a driving-gear of an electric automobile is achieved without upsizing a motor.

The driving-gear 10 is provided with a generator 25 driven by an engine 13 and the motor 14 which drives driving wheels by using electric power from the generator 25. An engine side input shaft 18 is linked with a crankshaft 22, and a motor side input shaft 19 is linked with a motor rotor 29. These input shafts 18, 19 are linked with an output shaft 20 which transmits power to the driving wheels. In an engine power transmission pathway 40a formed of the engine side input shaft 18 and the output shaft 20, a transmission 36 which changes number of revolution of the pathway 40a by multiple steps is arranged. When a vehicle is driven by the engine, driving force of the vehicle can be changed by changing number of rotation of the power transmission pathway 40a.