These The state of the aquatic environment in the Seto Inland Sea Japan has become a critical problem. Therefore the development of technology for improving and maintaining the aquatic environment and creating new habitats for marine organisms has become urgent. The present research and study as undertaken in order to develop a new CaCO3 porous material with high bio-affinity for use as a marine habitat. Material tests ere conducted to develop an effective porous material suitable for carbonation. Iron and steel slag (air cooled blast furnace slag) and concrete by-products of reconstruction were used as aggregate in forming the porous material and the void ratios and compressive strengths of the porous material ere studied. The porous material as carbonated, using special carbonation equipment, and the carbonation was observed by a scanning electron microscope. It was possible to confirm an increase in C (carbon) and a decrease in Ca (calcium) in the porous surface. An artificial reef of the CaCO3 porous material will be installed in the Seto Inland Sea and the effect of bait organism curing and organism aggregation will be verified by field observations.