As the new project of a deep submergence research vehicle following “SHINKAI 2000”, 6000 m vehicle is now under contemplation in Japan. One of the essential themes for a 6000 m vehicle is how to reduce the weight of the vehicle in order to achieve excellent maneuverability and operational efficiency. A pressure hull material with a high strength to density ratio is indispensable for this application. Some of the authors of this paper have been studying the material properties and fabrication procedure for both ultra-high strrength steel (10 Ni-8 Co Steel) and titanium alloy (6 Al4 VELI). As to 10 Ni-8 Co steel, the pressure hull fabrication procedure have already been established. As to titanium alloy, it was utilized for the small pressure vessels of SHINKAI 2000. In this paper, the authors have constructed the full-scale model of a titanium alloy (6 Al4 VELI) pressure hull, and established the fabrication procedure of the titanium alloy pressure hull.