The present invention improves mountability of a drive train in a hybrid vehicle by minimizing axial and radial dimensions while providing for adequate output torque of the motor/generator of the drive train. A center portion of a front cover of a torque converter extends axially and a multiple disc lock-up clutch is arranged at the inner circumferential surface of the center portion while the motor/generator is arranged at the outer circumferential surface of the center portion. A spring damper is provided at the radially inner side of a circumferential surface defined by friction plates of the lock-up clutch.