Abstract: Ito Jinsai, a representative of East Asian retro trend of thought, tried to transcend Zhu Xi Doctrine and go straight back to the doctrines of Confucius and Mencius by means of selfconscious criticism, and established the theory of Kogigaku which reserves traditional culture and makes innovation. The theory of virtue, which is at the core of Kogigaku, is unique in criticizing Zhu Xi doctrine and integrating the thought of Confucius and Mencius. He objected to the Sung Confucianism preaching “virtue” as “from the heart”, and regarded it as the general name of benevolence, righteousness, propriety and wisdom, and linked it with the meaning of “Tao”, thus interpreting the transcendental and noumenal meaning of “natural virtue”. He also criticized Sung Confucianism for taking the four cardinal virtues as nature, dividing nature into temperamental and original nature, and regarding Mencius theory of the goodness of human nature as the view that all nature is good. On the contrary, he integrated Confucius concept of “similar nature” with Mencius theory of “the goodness of human nature”, and concluded that nature has two characteristics of “disharmony” and “tending to be good”. From Ito Jinsais theory of virtue, we can not only know his unique construction of Kogigaku, but also reflect on the neoConfucianism construction of Sung Confucianism.

Key words: Ito Jinsai, original virtue, theory of the goodness of human nature, Kogigaku