Abstract In order for a ship to navigate safely, the qualifications of a navigator, various navigation equipment, and Aids to navigation(AtoN) are required. Among them, AtoN are mainly installed and operated by the Government, and if an individual installs it according to need, it can be installed and operated with the permission of the Minister of Oceans and Fisheries. In Korea, as of September 2021, 5,369(Government-owned 3,289 units, private 2,080 units) are in operation, and in Ulsan Port, 220 (as of '21.9) are in operation. There are 25 light buoys (10 units for 1 Fairway, 7 units for 2 Fairway, 8 units for 4Fairway). The role of the person in charge is very important as the review is carried out using various regulations and work knowledge when installing the AtoN. For the currently installed AtoN in Ulsan Port, risk analysis through maritime traffic flow and the visibility of the AtoN were evaluated to determine whether they were properly placed. As a result, the risk was high near Ulsan Port No.1 and 2 light buoys, Yangjuk Breakwater Lighthouse, and Jangsaengpo Port entrance, but it did not affect the evaluation of AtoN. The light buoys in operation on the Fairway were generally arranged within 1.15km, so it was judged to be appropriate. In the future, it is judged that safety accidents that may occur due to errors will be prevented in advance if a comprehensive review of the AtoN is conducted using risk analysis in sea areas necessary for maritime conditions, such as trade ports and Narrow channels.