As the depletion of land resources, the attention about marine resources has been focused on. Neighboring countries such as Japan and China to expand their marine territory invest more governmental money. The exact territorial sea baselines can be the scientific data which cad resolve the dispute between the neighboring countries. So, those territorial sea baselines should be maintained systematically and continuously. Because territorial sea baselines surveyed 10 years ago without updating, the review may be needed. In this study, we compared 2009 year surveying results with past territorial sea baselines results for reviews. As a results, Jeju Island represents a large difference. So, the outputs of territorial sea baselines around Jeju Island should be readjusted. Through this study, the ongoing maintenance of the territorial sea baselines is required. The continuing interest in the maritime boundary, as well as defend in terms of protection for undersea resources are needed.