This research is to extract the texts revealed in the Korea-China-Japan Trilateral Summit and analyze the meaning of 'cooperation' of them. To accomplish this, we conceptualized 17 related documents into 310 codes and categorized them into three items: perception in reality, challenges and future directions, and categorized them into values, tasks, areas, institutions, attitudes, and evaluations. And it came to the conclusion considering of word frequency and context and structurally explaining such as: First, the trilateral leaders defined the scope of cooperation very broadly and had optimistic assessments and values. In addition, they showed a respectful attitude towards the surrounding areas. Second, the issues of cooperation has been more and more moved to the public interests while the discussion on security was relatively not on the table. Emerging security issues have been reprocessed into alternative words -natural disasters, energy, etc.- but words related to traditional security -disarmament, nuclear, and weapon- appeared very few. It also does neither mention to the stability of the Korean peninsula nor North Korea issues. This means that the traditional security and North Korea issue are sensitive issues among three countries, but also are not easy topics to approach as a common concern at the Summit.
Although this research is limited only to concentrate on the given documents, it can give meaning to have reviewed the Trilateral Summit on the basis of texts, and deduced representation of cooperation among three countries leaders. Finally, this research is meaningful not only in terms of how the three countries recognize the intentions and limitations of cooperation, but also in terms of providing a systematic and objective follow-up study centering on texts.