PURPOSE: To improve engine response under acceleration/deceleration by monitoring the engine control state and correcting the relation between fuel supply considering A/F and intake air under transient state.

CONSTITUTION: Under operation of engine, a control circuit 10 will execute map retrieval of target opening of throttle valve θTH, fuel injection Tp and A/F on the basis of signals detected from an accelerator position sensor 9, a cooling water temperature sensor 11, A/F sensor 12 and a rotation sensor 13. Upon decision that the engine is under steady state, a throttle actuator 4 and an injector 5 are controlled in accordance to data θTH, Tp. While upon decision that the engine is under transient state, each data θTH, Tp is corrected in accordance to a constant to be provided as a function of ΔθTH thus to control the actuator 4 and the injector 5 in accordance to the correct data θ"TH, Tp".