The automotive industry has been researching and developing the green vehicle in response to the energy conservation and environmental problems recently. Especially, developing plug-in hybrid vehicles as the green vehicle is very active among many automobile manufacturers. The demand for plug-in hybrid vehicles is increasing compared to hybrid vehicles. A plug-in hybrid system and a transaxle, which enable vehicles to run as electric vehicles even in need of a high driving force for a powerful acceleration, are being required. We have developed a “Dual Motor Drive System” which enables vehicle to run with two motors by adding minimum number of parts as possible onto P610, which is the transaxle of the 4th generation Prius. For this system, we have used a generator as a motor which has been done by adopting a one-way clutch between an engine and a planetary gear. As a result, the new Toyota plug-in hybrid vehicle has achieved a powerful electric drive. This paper will explain “Dual Motor Drive System” and a structure of the transaxle.