To enhance motive power transmission efficiency and to reduce required capacity of motors in a driving device of the so-called hybrid automobile for transmitting motive power by using planetary gears by two kinds of motive power sources of an engine and plural motors.

This device has plural planetary gears 10, 20, 30, a first motor 58 and a second motor 68. The plural planetary gears 10, 20, 30 have a member A (a first ring gear 14) capable of restraining rotation to obtain speed reduction driving, a member B (a second sun gear 22) capable of restraining rotation to obtain speed increase driving and a member C (a third ring gear 34) capable of restraining rotation to obtain the intermediate transmission ratio of the speed reduction driving and the speed increase driving. Thus, the first motor 58 can be selectively connected to an output shaft 6 and the member C, and the second motor 68 can be selectively connected to the member A and the member B.