Dissolution rates of three basaltic rock samples from Japan (Fuji (sample1) and Hachijyojima (sample 2) fresh basaltic rocks, and Kitamatsuura (sample 3) altered basaltic rock) were experimentally determined in a pH range from 3 to 11 at 25°C. Initial dissolution rate constants are high (-9.9 ∼ -10.4 in logarithmic unit) . It is inferred that the initial dissolution rate is controlled by proton-cation (alkali, alkali earth and aluminium) ion exchange reaction and breakdown of Si-O bond in silicate. Long-term dissolution rate constants for Si determined are -11.5 ∼ -11.8 (in logarithmic unit) (sample1) and -11.3 ∼ -11.8 (sample 2) . These values are lower than those for artificial basalt glass previously obtained. The rate constant determined for sample 3 is consistent with those of feldspar previously studied. In future based on the present results on the dissolution rate of basaltic rocks, we will perform calculation on the temporal changes of the amount of carbonates precipitating from groundwater reacting with basaltic host rocks in order to estimate the amount of CO2 fixed by mineral trapping for underground CO2 sequestration in basaltic rock area in Japan.