This paper presents a new method of explosive welding using underwater shock waves. The method renders the possibility of accelerating a thin metal plate uniformly at a velocity above a few hundreds m/s to satisfy the explosive welding requirements. The welding of a thin titanium plate onto a stainless steel base and other welding experiments were performed underwater. The bonding strength at the interface is observed to be high because the materials are welded based on the mechanism of explosive welding. The experimental results are discussed to characterize the state of bonding.