Abstract: A novel device of the present invention detects an abnormal driving condition where a sub-throttle valve pressed in a full-opening direction by means of a spring is abruptly driven in the full-opening direction due to an abnormal condition of an actuator, and controls an internal combustion engine according to the requirements. A difference DLTA in an opening TA of a sub-throttle valve 34 within a preset time period is determined (steps S100 through S130) and then compared with a predetermined range allowing to be driven by a stepping motor 32 (step S140). The sub-throttle valve 34 is pressed in a full-opening direction by means of a spring 54. In case of a step-out of the stepping motor 32, the sub-throttle valve 34 is abruptly driven in a full-closing direction by the spring 54. When an abrupt change of the sub-throttle valve 34 is detected, a process under abnormal conditions (abnormality process) including reduction of fuel injection is implemented (step S160).