Wusoh written by Yu, Suwon is one of the social reform document beyond Adam Smith's masterpiece(An Inquiry into the Nature and Causes of the Wealth of Nations). In early 18th century he sharply analyzed the cause of weakness and poverty of nation and proposed the way how to make it wealthy and to stabilize the life of grass-roots. It is specially important that he emphasized the division of labor among the 4 classes(scholar, farmer, artisan, merchant) and the equality of jobs. He understood the importance of utilitarian aspect and executive power of science to run government, as many other philosophers of Practical Learning in the late Lee dynasty. It is noteworthy of his viewpoint of national productivity increment among many philosophical thoughts. His idea is following. First policy was to increase the national productivity through the division of labor and job specialization. Second was to let people understand sacred value and importance of their jobs and to lead it to the expansion of employment. It would naturally enhance the national productivity. Third idea is to make strong finance by introducing rational tax system. Fourth way of national productivity increase was to maintain proper economic size. Fifth was the technical renovation of agricultural industry for increasing agricultural productivity. The sixth policy was the promotion of market, which eventually would strengthen the national competitiveness.It is necessary to look back the footsteps of forerunners, when our nation has hard time. Up to this time we followed western economy blindly, but it is important to find our own way. The grafting our own economic science onto the western can be a nice way of reviewing old and learning new.