To improve evacuating drive performance when abnormal condition occurs in an electronic throttle system of an engine.

When major abnormal condition occurs, a first abnormality memory element 133 operates to de-energize a power source circuit load relay 104a of a throttle valve switching control motor 103 and then activates a first alarm and indicator 109a, so that the evacuating drive is performed by a first means using fuel cutting control. When minor abnormal condition occurs, a second abnormality memory element 136 operates to activate a second alarm and indicator 109b, so that the evacuating drive is performed by a second means using throttle valve travel control and the fuel cutting control at the same time.