To provide a hybrid vehicle drive system for improving regeneration efficiency without co-rotating an engine when regeneration is performed by a motor generator, and a control method thereof.

A hybrid vehicle drive system comprises: a first clutch CL1 for connecting or disconnecting an output shaft 1 of an engine ENG with or from an input member 3 of a transmission TM; a second clutch CL2 for connecting or disconnecting the output shaft 1 of the engine ENG with or from a rotor 2 of a motor generator MG; and a third clutch CL3 for connecting or disconnecting the rotor 2 of the motor generator MG with or from an input member 26 of a transmission mechanism GS. The first clutch CL1 and the transmission TM are arranged on a first power transmission path 11, and the second clutch CL2, the motor generator MG, the third clutch CL3 and the transmission mechanism GS are arranged on a second power transmission path 12. The first power transmission path 11 and the second power transmission path 12 are provided in a relation parallel to each other. When regeneration is performed, control means 60 turns off the first clutch CL1 and the second clutch CL2, and turns on the third clutch CL3.