In Japan, space utilization of the ocean has been considered as one of the most important subjects. Therefore we thought out a new type structure for ocean space utilization which can be installed in the ocean of water depth 3070m. This structure is composed of a semisubmersible type ring-like structure and supporting foundations. For the sake of investigation of structural feasibility of this ring-like structure, the steps of procedure taken in this paper are as follows ; (1) concept design of a new type structure, (2) setting of natural environmental conditions (wind, current, wave, earthquake) and designcriteria, (3) initial structural design, (4) evaluation of external forces using wind tunnel tests and a source distribution method, (5) structural response analysis using FEM.