The present invention allows for the engine speed at the start of a shift transmission operation to be maintained during a shift transmission operation until an engaging operation of a clutch device (6) is performed in a vehicle in which a manual transmission (MT) and a clutch device (6) are mounted. This makes it possible for the engine speed to be maintained at a substantially intermediate rotational speed between a synchronous rotational speed after shift transmission when the manual transmission operation is a down-shift operation and a synchronous rotational speed after shift transmission when the manual transmission operation is an up-shift operation, and it is possible to reduce the deviation between the rotational speed of an input shaft (IS) and the engine speed, as well as to reduce the adverse impact on the power transmission system when the clutch device (6) is jointly engaged, irrespective of whether the manual transmission operation is a down-shift operation or an up-shift operation.