A hybrid transmission for variably producing a transmission ratio is comprised of first and second motor/generators (MG1 and MG2) and a differential mechanism constructed by two double-pinion planetary gearsets (2 and 3). The two double-pinion planetary gearsets are coaxially arranged and commonly employ common pinions (P1). The differential mechanism includes at least four rotating members which are interlinked so that rotating conditions of all of the rotating members are determined when rotating conditions of two of the rotating members are determined. Four of the rotating members are connected to an input from a prime mover, an output to a driveline, first and second mover/generators, respectively.