On December 31, 1977, Korea enacted the territorial waters Act and declared the scope of territorial waters at 12 nautical miles. The territorial sea refers to a part of the national territory of a coastal country, which is part of the territory of a coastal country, which has the right to set the width of the territorial waters from steamers determined under the U.N. Convention on the Law of the Sea to a limit not exceeding 12 nautical miles. Twelve nautical miles are the principle from territorial vessels, and foreign ships enjoy the right of free passage. The security of the territorial waters is an important function of the maritime police, which is very important, as there are national key industrial facilities near the territorial waters, such as the building of public institutions, airfields, airports, ports and port facilities, and other power plants, shipyards, steel mills and oil reservoirs, and there are many important national facilities that require special protection for the national security or public interest. Researches of this paper is a Japanese Maritime Safety Agency, a review of the Act on the navigation of foreign ships in territorial waters in territorial waters. Comparison of Korea and Japan for the navigation system, implications and discuss how to improve. Among the problems of the Korean legislation were the lack of specificity in the Territorial Sea and Contiguous Zone Act, and the limitations of the Coast Cuard Affairs Act. As an improvement measure, it is necessary to propose the enactment of the Act on the Passage of Foreign Ships in the territorial waters, which imposes an obligation to notify the maritime police when foreign ships stop, anchor, moor, or wander. and makes regulation to conduct maritime inspection if they violate the law. It is also necessary to specify recommendations, guidance and eviction orders.