A long distance measurement system using a stereo camera mounted on a rotation control device is proposed for automatic ship control, and the performance of the system is presented to verify the usefulness of it. As a solution to prevent ship operators from maritime accidents owing to their strain for a long period, the distance measurement system is often required to automatically control the posture or berthing of a ship. Here, we discuss the system structure suitable for used environment and its experimental results. From the experiment conducted to imagine the distance measurement necessary to altering the posture and translational motion between a ship and its facilities, the average error for the range of 20 to 100 m was less than 1 percent.