Tasan s theory of emotion in previous studies has tended to be interpreted as an extension of the Four-Seven debate of Joseon Confucianism. However, Tasan s approach to emotions(whether moral or not) differs in many respects from his predecessor Confucian. Tasan sets the dual world, Qi(氣, the material) and Ling(靈, the spiritual), and claims that the substance of Spirit is directly received from Heaven. This gives us the possibility of a pure manifestation of Tao mind emerging from the substance of Spirit and immediate awareness of it. With this feature in mind, I assert some propositions: First, the key to self-cultivation in Tasan philosophy is in awareness and preservation of the Tao mind, not in reducing or eliminating desires. Second, in spite of realistic difficulties, ethical practice is only possible through the Tao mind which works as the incentive of the moral disposition, and there is no antecedent feeling with regard to moral behavior. Third, Human mind is stimulated with anxiety from the four modification of the Tao mind, and the recognition of supreme god reinforces the mental state of this anxiety through the reverential fear. Fourth, Tasan distinguishes between Jieshen(戒愼, Humiliation) and Kongju(恐懼, Reverential Fear) presented in the way of strengthening the Tao mind. Tasan sees that Humiliation is possible through the inner conscience of Tao mind, but the reverential fear can not be assumed without existence of the supreme god. Fifth, in Tasan s theory of ethics, happiness(樂處) is provided as an object of intention or an ideal to be realized in the future, not in reality.