Until now, research on inter-Korean economic cooperation and economic integration has been limited to the areas of the two Koreas. However, Korea is connected with many countries in Asia through the global value chain. Thus, if inter-Korean trade deepens, it may affect the trade structure of neighboring countries. In order to establish a specific inter-Korean economic integration policy when North Korea becomes a normal state in the future, an analysis that reflects the trade structure including Northeast Asia must be preceded. Therefore, in this paper, the impact of inter-Korean trade on Korea, China and Japan was analyzed using the international input and output table containing actual trade data. The scope of analysis was limited to agriculture, reflecting North Korea's demand for economic cooperation. The results show that trade in the agricultural sector between the two Koreas did not have a significant effect of production and value added. but when China and Japan participate in trade with North Korea, the production effect was calculated to be as high as 4 million dollars in Korea and up to 10 million dollars in Japan. And China showed up to 520 million dollars. In addition, the value-added effect was calculated up to $1 million in Korea, up to $4 million in Japan, and up to $250 million in China.