Dissolution kinetics model calculations were performed for the interaction between three types of basaltic rocks in Japan (Fuji and Hachijyojima fresh basalts and Kitamatsuura altered basalt) and groundwater injected CO2. Dissolution rates of the basalts experimentally determined by the authors (Shikazono et al., 2008) and database of dissolution rate constants of silicate minerals in the basaltic rocks in PATHARC (Talman et al., 2000) were used for the calculations. The results of calculations indicate that most of dissolved carbon in groundwater injected CO2 can be fixed as carbonates in long-term period. The efficiency of carbon fixation is in an order, Hachijyojima>Fuji>Kitamatsuura. But the efficiency is not so different for three basaltic rocks in the fixation of carbon in underground sequestration of CO2. It is inferred that mineral trapping of CO2 by carbonates in basalt aquifer is useful for the long-term fixation of carbon in underground sequestration of CO2.