Leisure boat and yacht should be designed to meet the domestic regulation and international standards as large merchant vessels do. Recently, each countries are encouraged to follow the regulation of International standards organization. Furthermore domestic organization has not yet announced the design rule and regulation for FRP-catamaran yacht design. Therefore, it has been required to make the regulation for domestic situations of FRP-catamaran. This study deals with the structural strength evaluation of 50ft catamaran by using finite element analysis. Design load of the regulation of International standards organization are compared with the regulation of Korea Register of shipping and Lloyd's Register.