This study describes and discusses the marine accidents investigation & inquiry system of Korea, U.K., U.S.A., the Netherlands and Japan. As the results of the comparison of them, the following recommendations are made with respect to improve the system in Korea. (1) The Agency should be independent from the central Government with respect to the budged, personnel management and a agency building. (2) The inspection function and judgment function should be divided into separate Agency. (3) The Agency should has a recommendation right to Government agency according to the results of investigation. (4) The composition of inspectors & judges must be diversified including navigation, marine engineering and naval architecture background. (5) The Agency should have co-operative system with the Marine Police Agency. (6) International affairs division should be included in the Agency to promote international relations.