A throttle control CPU drives an electric motor throttle valve control based on an accelerator position. When detecting an abnormality in the throttle opening control system, a main CPU stops driving the electric motor and controls fuel injection amount and/or ignition timing to curb engine output torque increases otherwise caused by a valve opening movement (performed until a cooperative member connected to the throttle valve contacts a restricting member mechanically connected to the accelerator pedal). Thereafter, opening of the throttle valve is regulated according to the accelerator pedal position while the restricting member and the cooperative member remain in contact. The control apparatus smoothly shifts the throttle opening regulation to the fail-safe mode when an abnormality occurs by actively controlling engine speed changes during mode transition.