The present paper reports the experimental and numerical study of shock wave propagation under saltwater sealed in aluminum containers. This study is the fundamental research on shock sterilization for development of ship's ballast water treatment technique. In the experiment we carried out the impact experiment with a gas gun to generate strong shock waves in saltwater. We confirmed that no leakage of saltwater from the aluminum container was obtained after shock events. The shock pressure fluctuations were measured with piezofilm gauges. Several hundred MPa pressure behind the first shock wave under the saltwater was obtained by the experiments. The FEM simulation, using the Johnson-Cook model for aluminum material and the Tait equation for salt-water, was carried out in order to predict the shock phenomena in both aluminum and saltwater. The computational results showed the states of stress and pressure in the container and indicated good agreements with the experimental results on the first shock pressure profiles at the impact velocities less than 200 m/s qualitatively and quantitatively.