A first planetary gear mechanism (P1) transmits the rotation of a first main shaft (13), to which drive force from an engine (E) is input upon engagement of a first clutch (C1), to a main speed-change unit (P2) at the same speed, while transmitting the rotation of the first main shaft (13) to the main speed-change unit (P2) and a first motor generator (MG1) at an increased speed upon engagement of a second clutch (C2). Thus, the range of gear ratio of a transmission (T) can be increased while also increasing the degree of freedom of setting the gear ratio or a step ratio. In addition, the first motor generator (MG1) can be caused to rotate at high speed for increased generation efficiency without requiring a special speed-increasing means. Further, the same-speed transmission of rotation of the first main shaft (13) to the main speed-change unit (P2) eliminates the demand for excessive speed-reduction ratio from the transmission (T), so that friction loss can be reduced and the size of the transmission (T) can be decreased.