The investigation of marine accidents in Korea can not handle the international codes and guidelines and is being followed the conventional methods with a big gab to the international criterion and procedure. Also there is no proper investigation manual which is cope with the new era and surrounding circumstances. This study analyzed the investigation manual of other countries, and proposed new investigation manual according to the analysis and international standards and procedure as followings; (1) Develop own investigation manual separating from the field manual which is mixed with judge, (2) Correct and improve the error and hazy words in the existing field manual which is not compatible a current situation, (3) The contents of new manual should be changed to cope with the international rules, criterion and procedures. The list of contents and index is added, an abundant explanation and examples are given, and charts and illustrations are inserted to make the users understand easily. Also the inquiry techniques according to the classification of each accidents are included.