This paper proposes a vision-based, closed-loop target-following system for quadrotors. The system consists of a vision-based target detection algorithm that uses the color and image moment of a given target. Flight control commands are directly generated based on the offset of the target from the image frame center. The image processing and control algorithms have been implemented on a latest tablet computer, which is capable of running those algorithms in real time. The proposed system was demonstrated using a commercially available quadrotor platform equipped with a forward-facing camera. Experiments and their analyses showed satisfactory target following performance.