PURPOSE: To perform running taking refuge arbitrarily even in the case of generating a trouble in a motor by controlling an opening of an ISC valve by an accelerator opening which is electrically detected at fail time of the motor for opening/closing a throttle valve.

CONSTITUTION: In an ECU 11, a throttle opening is calculated by an output from an accelerator opening sensor 12, and in accordance with the calculated throttle opening, a throttle opening request signal is output to a throttle valve driving motor 14 to control a throttle valve 13 to a desired throttle opening. Here at fail time of the motor 14, the ECU 11 controls an opening of an ISC valve 15 by an accelerator opening. Thus by controlling an engine speed by the accelerator opening, arbitrary running of taking refuge can be performed even in the case of generating a trouble in the motor 14.