In the disclosure, an F/B correction coefficient correcting a fuel injection amount so that a detected equivalence ratio detected by an LAF sensor becomes a target equivalence ratio is calculated by using a feedback control containing a predetermined gain, and a reference F/B correction coefficient is further set. By changing a valve overlap characteristic between an intake valve and an exhaust valve in a supercharging state, a scavenging control that scavenges a combustion chamber by blow-by of intake air is executed. During the scavenging control, when the F/B correction coefficient is changing relative to the reference F/B correction coefficient in a direction of further correcting the fuel injection amount to a rich side, the gain of the feedback control is reduced.