provided are an optical pointing apparatus and an automatic gain control method thereof . the optical pointing apparatus includes : an image sensor comprised of a plurality of pixels , for receiving light reflected by a work surface , sensing image data , and outputting an electrical signal ; an automatic gain control unit for receiving the electrical signal , controlling the gain of the electrical signal according to brightness and darkness from images of the work surface and the motion speed of the optical pointing apparatus , and outputting a gain output signal ; and an image data processor for receiving the gain output signal , analyzing brightness and darkness from images of the work surface to control the gain of the electrical signal , detecting the motion speed of the optical pointing apparatus to control the gain of the electrical signal , and calculating and outputting the motion speed of the optical pointing apparatus .