In order to generate the underwater shock wave with ultra-high pressure and good controllability, we have developed the underwater shock wave system with pulse power machine, which consists of a Marx generator and a pulse forming line. Characteristics of the underwater shock wave generated by a high current short pulse discharge have been studied by a PolyVinylidene DiFluoride(PVDF) pressure transducer and laser shadowgraphic method. When the output voltage of Marx generator was 150 kV and the discharge gap distance was 10 mm, the underwater shock wave with peak pressure of 313 MPa and average propagation velocity of 1750 m/s was observed at 30 mm downstream from the electrode axis.