This study develops an index for each of corporate financial performance, operational performance and organizational effectiveness, with the view that these disparate elements constitute corporate performance. Human resources indexes are also developed under the assumption that corporate human resources system is likewise multi-dimensional, encompassing such factors as human resource development, performance evaluation/compensation, and the competence of human resource management (HRM) division. Using these indexes, this paper examines the effect of the firm's investment in human resource development and management (HRD/HRM) on financial performance, operational performance, and organizational effectiveness of the firm. The factor analysis was used to develop the indexes for human resources system and corporate performance. The empirical analyses are based on data from the first two Human Capital Corporate Panel (HCCP) surveys conducted by Korea Research Institute for Vocational Education & Training (KRIVET) in 2005 and 2007, as well as on the corporate financial information for years 2005 and 2007 as provided by Korea Information Service(KIS). The OLS regression analyses reveal that the firm's level of HRD/HRM as a system has a significant positive impact on financial and operational performance and organizational effectiveness of the firm. On the other hand, the human resources system index, controlling for the endogeneity of corporate human resources investment, indicates that any meaningful positive effect of HRD/HRM is limited only to per-employee sales.