A control unit performs a vehicle attitude control to reduce a torque generated by an engine when an increase in a steering angle exceeds a standard increase, and a spark ignition controlled compression ignition combustion in a predetermined operating range. In the spark ignition controlled compression ignition combustion, switching of an air-fuel ratio mode is performed between a first air-fuel ratio mode (λ>1) is formed and a second air-fuel ratio mode (in which a mixed gas of λ≤1) is formed. If the switching of the air-fuel ratio mode is requested without the vehicle attitude control, the control unit allows performing the requested switching of the air-fuel ratio mode. In contrast, if the mode switching is requested in a state where the vehicle attitude control is requested, the control unit disallows switching of the air-fuel ratio mode even when the switching of the air-fuel ratio mode is requested.