of the accelerator position is limited to a value equal to or below the upper limit change rate the detection value apo from the selected accelerator position sensor 1 a or 1 b during single failure of the accelerator position sensor the detection value of the sensor diagnosed as normal the switched selected upper limit value apo limiter and the accelerator position performed of the above u03b4apo limiter process are inputted to a select low circuit 38 and the smallest accelerator position of all values is selected and used accordingly as shown by the thick continuous line of fig6 b the absolute value of the accelerator position is limited by the upper limit value apo limiter and the increase change rate is limited by the upper limit change rate u03b4apo limiter by the control of the throttle valve position corresponding to the limited accelerator position characteristics a limp home control may be performed where rapid acceleration is restrained and increase of absolute speed is also restrained further in a simplified system only the absolute value of the accelerator position may be limited by the upper limit value or only the increase change rate may be limited by the upper limit change rate when both two accelerator position sensors 1 a and 1 b throttle position sensors 11 a and 11 b fail to operate the throttle position may not be controlled normally so though not shown in the drawing the power supply to the actuator is stopped and the throttle valve 9 is maintained at a predetermined default position realized for example by the.