The purpose of this study is to analyze the encounter patterns between merchant ships and fishing vessels. The study area is set as TongYoung coastal vts control area. It is an area suitable for study because the number of fishing boats in the area is the largest in korean territorial sea. To analyze the traffic pattern, traffic data for 365days in 2017 was collected and was based on AIS signal. I got the result that the number of fishing boats groups with certain patterns were four in the area. The encounter pattern between each of the four groups and merchant ships were analyzed. As a result, the areas which has specific encouter pattern between each fishing boat group and merchant ships were found. And one of several area which each fishing boats has encounter pattern with merchant ships were matched. The area is also the most heavy traffic area of merchant ships. This study would be helpful for preventing from marine accidents.