To provide a controller whose responsiveness to speed change improves by quickly changing the rotational speed of an engine at speed change control of a stepped automatic transmission, in a drive unit for a vehicle which is equipped with a differential mechanism and the stepped automatic transmission.

An overall transmission mechanism 10 is equipped with a motive power distributing mechanism 16 that is so constituted as to selectively switch a differential state where a continuously variable transmission part 11 is enabled to work as an electric stepless transmission and a non-differential state where it is disabled, being equipped with a change-over clutch C0 and a change-over brake B0. An engine rotational speed control means 84 controls the rotational speed NE of an engine, using the differential action of the motive power distributing mechanism 16, at speed change control of a stepped transmission part 20. Therefore, regardless of whether the changeover of the speed-changing stage of the stepped transmission part 20 is started or not, the rotational speed NEof the engine is changed quickly, thus the responsiveness improves, concurrently the speed change control of the stepped speed changing part is executed, so the speed change control finishes quickly.

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