PURPOSE: To effectively restrain creation of discomfortable vibration by providing both a power transmitting mechanism which transmits power to a supercharger and a controlling means which reduces the number of specific cylinders when operating range of the supercharger is shifted to another range.

CONSTITUTION: When a supercharger-on range is identified at a step 201, the step then shifted to a next step 204. If the range was identified to be the off range in the precedent operation, a solenoid clutch is turned on at a step 206 and an operational indication of reducing the number of cylinders is generated at a step 207. Such condition of cylinder number reduced injection operation is kept for a period T1 which is set at a step 209. On the contrary, if the supercharger state is in an on range on the basis of the precedent determination at a step 202, an operational indication of reducing the number of cylinders is produced at a step 209 and such condition of cylinder number reduced operational indication is kept for a period T2 which is set at a step 210. The operation controlling condition of a vehicle is thereby smoothened greatly so that creation of discomfortable vibration may be restrained effectively.