Jung Da-San(1762-1836) was born in Reungnae-ri Wabu-myon Yangju-gun Kyonggi-do and buried there. He led his life through the greatest disordered era when the people then were severely distressed amidst the political disorder, injustice and corruption of the public officials, which were then widely spread nearly all the corner of Korea. In spite of his miserable political exile under these disarranged circumstances, he spent most of his lifetime in studies which can renovate the corrupt and chaotic society. This paper aims to study the essential point of his ethic thoughts. This study can be summarized as follows: Jung Da-San attended to set up his learning under direct influence of the Confucianism while he ruled out any other theories of the Study of Human Nature and Natural Law of Song Dynasty and the Exegetics of Han Dynasty. It was his firm belief that the Great Learning should be rooted in filial piety, fraternal love and maternal virtue. The essence of his ethic thoughts lies in realising the above three virtues, filial piety, fraternal love and maternal virtue, at the same time emboding his political views and his beneficent will. He looked upon it as the most desirable ruling method that the governor should always rule his country with beneficence such as that of parenthood. Besides he should be disinterested and never distort the public and official services by way of his private intention. All the political power and power-consciousness of governor come into being to rule the country only for the benefit of people and not for any private profit. Jung Da-San also stood to the opinion : if the power and function of governor were against its own people-oriented duty, even the royal power was to be turned down and given way to any new revolutionary regime. In the family precepts he gave to his disciples he expressed that they should do their utmost to accomplish the three virtues, namely, filial piety, fraternal love and maternal virtue by way of leading their life in diligence and frugality. He emphasized these three virtues, that is, filial piety, fraternal love and maternal virtue which were based on the family ethics but he stressed far the fact that the family-based ethics would be widely elevated and be finally led to the social-wide ethic thoughts. The ethic pedagogism of Jung Da-San can be said to envisage the exemplary notion of public officials through cultivation of self-achivement.