This article is a study to suggest about the illegal fishing problem of chinese fishermen in the five islands of the West Sea. The illegal fishing problem of chinese fishermen is international affairs in Far East. Especially, Frequency of Chinese fishermen’s illegal fishing more in the northern line sea than in another seas. Vessels of chinese fishermen come and go across northern limit line to evade regulation of south korea’s coast guardmen with guerrilla technique. On the occasion of regulating by south korea’s coast guard men, they go to north korea sea. This illegal acts was happened in nighttime or worse weather conditions. The illegal fishing problem of chinese fishermen in the five islands of the West Sea became not only the problem of south korea and china but also the problem of south korea and north korea. therefore, three nations(south korea, north korea and china) were related to the illegal fishing problem. I suggest that authority of south korea should try to approach “Special Zone of Peace and Cooperation in the west sea” initiative, reestablishment of south korea and north korea agreement to prevent illegal fishing in the NLL, the fishing cooperation of south korea and north korea, the foundation of coast guard station in the NLL area and the regulating ability reinforcement of korea coast guard about illegal fishing chinese fishers.