In a hybrid transmission, input and output side motor/generators (MG1, MG2) and input and output portions (In, Out) are coupled to two sets of the differential units (G1, G2) in such a manner that, under a selection of a first predetermined gear ratio, in a revolution speed order, the input side motor/generator (MG1), the input portion (In) from a prime mover (engine), the output portion (Out) toward a vehicular drive system, and the output side motor/generator (MG2) are coupled to the respective revolvable elements of the two sets of the differential units (G1, G2) and the output side motor/generator is coupled to any one of the revolvable elements of the two sets of the differential units including those revolvable elements thereof which do not contribute to a revolution of the output portion.