Research on the development of Super High-Speed Container Ship was already reported. In that research it was pointed out that there are some weak points on the transverse stability and turning ability. So, for overcoming these points, we considered vertical active fin under the middle bottom of the ship, and confirmed its effectiveness by model experiments in directional spectrum waves generated in the towing tank of Yokohama National University. Furthermore, we developed numerical simulation program for estimating coupled Roll-Sway-Yaw-Surge motion on a calm water and compared with experiments. One example showing the increasing the turning ability using vertical fin is also presented.