This article checks the Neo-Confucianism of Toegye. By including the former analysis and research of result, it investigates only the trend of research realized from the beginning of 1990s to 2008. Considering sense of problem and research target found in the research of Toegye science instead of using the typical method to divide age, it classified and investigated in 3 trends of research. They are research on the predisposition of Li-Ki & Mind-Nature, ‘Toegye Mind science’ and Seong-Hak-Ship-Do. While the first has drawn attention constantly since Toegye science has been studied philosophically, the second was sense of problem that appeared as it was designated as the research centering around Mind-Nature theory as the feature of Korean Neo-Confucianism which was different from that of China when the first was studied intensively and the issue of relation with the Neo-Confucianism of Yuan and Myung was presented. Entering 1990s', this was formed as trend, triggering controversy. The third may be deemed to be studied in connection with the 2 former areas and its independent area might be recognized later. The task required in this point is presented, though it is the subjective judgment of author. First, it is required to convert the viewpoint that can view universality rather than difference. Toegye is a great scholar, because he shares the universal truth and value of human and concretely spreads them through his learning and life in addition to his difference from others. Second, it is suggested to actively recognize the essence of Toegye science. Reading Toegye without present sense of problem may fall into classicism that is separated from reality. However, if reading Toegye to completely restore the life and ideology of Toegye can be loyal to the purpose of questing the universal truth, it may be distant from the ideological classicism. Third, it must be able to satisfy the demand of modern science on the basis of wholly restoring Toegye science. Some people tend to think that quoting the scholarly factor of Toegye, criticizing modern life and exhorting it ethically is the application of Toegye science. Thinking that the ultimate goal of research and integration of between educational systems currently discussed is the reconstruction of metaphysics, the author considers that research on the Toegye science may intervene with this issue to some extent.