The bottom of deep sea is one of the fields where robots can work advantageously. This paper introduces a prototype of robot for deep sea survey, which was developed at the University of Tokyo and designated as “PTEROA 150”. The body is designed to decrease the drag force for cruising. To improve controllability for pull-up maneuvering, a pair of horizontal elevators is fitted at the stern. Computer simulation of swimming proves that the longitudinal stability and maneuverability of this robot are suitable for the mission.