1. An apparatus for compensating auto-focus of image capture device by utilizing red-eye eliminating function comprising: an image sensor for capturing an image of an object so as to determine a focal length evaluation value of the object; a focal length adjuster for adjusting a focal length of the image capture device; a red-eye eliminating device capable of flashing for providing a red-eye eliminating function; and an auto-focus module for preliminarily determining a distance from the object to the image capture device based on the focal length evaluation value of the object captured by the image sensor to drive the focal length adjuster for performing a rough adjustment of the focal length of the image capture device, and when the red-eye eliminating device flashes for eliminating red-eye effect, further determining the distance from the object to the image capture device based on the focal length evaluation value of the object captured by the image sensor to drive the focal length adjuster, thereby performing a fine adjustment of the focal length of the image capture device