To solve the problem that when a certain cylinder is stopped and secondary air is supplied in regard to exhaust gas of the remaining operating cylinders, the amount of the secondary air is sometimes insufficient.

An ECU determines whether a secondary air supplying condition is fulfilled or not (S10). If the condition is fulfilled (Y of S10), the ECU cancels fuel injection from an injector equipped to a first cylinder and ignition of an ignition plug (S12), closes an opening and closing valve (S14), changes the valve timing of a first suction air valve and a first exhaust valve (S16), and makes the stopping cylinder function as an air pump.