1. An image-based hand detection apparatus, comprising a hand image detection unit for detecting a hand image corresponding to a shape of a hand clenched to form a fist from an image input from a camera; a feature point extraction unit for extracting feature points from an area, having lower brightness than a reference value, in the hand image detected by the hand image detection unit; an image rotation unit for comparing the feature points of the detected hand image with feature points of hand images stored in a hand image storage unit, and then rotating the detected hand image or the stored hand images; a matching unit for comparing the detected hand image with the stored hand images and then generating a result of the comparison; and a hand shape recognition unit for, if at least one of the stored hand images is matched with the detected hand image as the result of the comparison by the matching unit, selecting the at least one of the stored hand images as a matching hand image.