To arrange a motor-generator and a torque converter between an engine and a transmission in a compact manner.

A power transmission device for a hybrid vehicle is provided with the motor.generator MG arranged in parallel between a crank shaft 22 of the engine E and a main shaft Sm of the transmission T and the torque converter 23. A lock-up clutch 85 of the torque converter 23 composed of a wet multiple disk clutch and a damper 95 absorbing the fluctuation of output torque of the engine E are stored inside a rotor 61 of the motor-generator MG. Consequently, the motor-generator MG and the torque converter 23 can be miniaturized, and a distance between the engine E and the transmission T can be reduced to miniaturize a power unit.