This paper presents a supporting system for pool games by computer vision based augmented reality technology. Main purpose of this system is to present visual aids drawn on a pool table through LCD display of a camera mounted handheld device without any artificial marker. Since a pool table is rectangle, a pool ball is sphere and each has a specific color, those servo as a substitute for artificial markers. Using these natural features, the registration of visual aids such as shooting direction and ball behavior is achieved. Also, our supporting information is computed based on the rules of pool games and includes the next shooting way by simulating ball behavior. Experimental results represent that the accuracy of ball positions is enough for computing our supporting information.