Conventionally, a hybrid vehicle including a transmission mechanism that changes the rotation speed of an engine and transmits the rotation of the engine is known. For example, a driving device of a hybrid vehicle described in Patent Literature 1 includes a transmission mechanism that changes the rotation speed of an internal combustion engine and transmits the same to a power distributing mechanism, a first transmission shaft that transmits the power from the internal combustion engine to the transmission mechanism, and a second transmission shaft that transmits the power output from the transmission mechanism to the power distributing mechanism. The transmission mechanism includes a differential mechanism in which two sets of planetary gear mechanisms are combined, a first brake B1 that can stop the rotation of a ring gear R1 of the differential mechanism, a second brake B2 that can stop the rotation of a ring gear R2, and a clutch C that discontinues the power transmission from the first transmission shaft to the ring gear R1.
According to the driving device of the hybrid vehicle according to Patent Literature 1, a direct transmission torque can be increased to reduce a torque of a rotating electrical machine while preventing lowering of fuel efficiency at the time of light load, and sufficient backward movement drive force can be ensured.