An apparatus of controlling an electronically controllable throttle valve for car has a sensor for detecting the opening of the throttle valve and a microcomputer. A throttle valve opening command value is delivered in the form of a digital signal under the control of the microcomputer. The digital command value signal is converted into an analog signal and on the basis of the analog signal and a detected throttle opening, a motor connected to the throttle valve is driven to control the opening thereof.