The purpose of this study was to investigate the relative effects of human capital and social capital on the economic well-being of late middle-aged Koreans. The data from the first wave of KLoSA (Korean Longitudinal Study of Aging) aged 50-64 were used (n=4,040). The major findings were as follows: First, human capital and social capital are both resources that can contribute to increasing the economic well-being of the middle-aged. Second, the relative contribution of human capital to the economic well-being of the middle-aged varied by the level of social capital, including formal network and informal network. Third, the relative contribution of social capital to the economic well-being of the middle-aged varied by the level of human capital, including employment type and educational attainment. Based on empirical results, the implications for social investment in human capital and social capital were provided.