Upon shifting control of differential mechanism 10, speed ratio .gamma.0 of continuously-variable transmission portion 11 and speed ratio .gamma. of automatic transmission portion 20 are determined by vehicle-output control device 82 on the basis of target engine output P.sub.E* and vehicle speed V, so as to establish an operating point of engine 8 which provides the target engine output P.sub.E* and which follows an optimum-fuel-economy curve, and the shifting control of the continuously-variable transmission portion 11 and the shifting control of the automatic transmission portion 20 are effected substantially concurrently, so that engine speed N.sub.E continuously changes, and the differential mechanism 10 is shifted with a reduced shifting shock. Further, the speed ratio .gamma.0 of the continuously-variable transmission portion 11, in other words, the engine speed N.sub.E is changed by using first electric motor M1 and/or second electric motor M2, permitting an improvement in shifting response of the differential mechanism 10.