The pressure hull for deep submersible has to cope with the trade-off subject of load carrying capacity and minimum weight at the same time. For this reason, spherical shell has been normally adopted for the pressure hull. Besides this, high yield strength materials and high-precision manufacturing are indispensable for it. The authors have already confirmed that GTA welding is effective for the pressure hull of 6, 000 m class of 10 Ni-8 Co steel. However recently, electron beam welding, which has the possibility to reduce welding distortion in comparison with GTA welding, has come to withstand this objective. The authors, in this paper, have estabilished the effectiveness of EBW for the pressure hull of 6, 000 m class of 10 Ni-8 Co steel.