In recent years, many types of autonomous underwater vehicle AUV (Autonomous Underwater Vehicle) have been used in various surveys in water. Since AUV is operated and navigated autonomously without tether cable that connects its mother ship, we can save human resources in accordance with the operation, and also we have an advantage of not subject to the constraints of the mother ship with respect to the moving range. For those reasons AUV is often used in the mission of underwater mapping. In those missions, we need to choose and put suitable sensors on AUV according to observed objects. Some types of AUV, like HUGIN (shown in Figure 1 [1], Kongsberg), can partition their body into some module, and we can replace modules to replace sensors according to the mission. We can connect many modules to use many function, but the more modules we use the larger the vehicle size is, and controllability, including the turning performance is going to become worse. In this study, we propose “Train type AUV” which uses movable joints and cables and explain its possibility.