To study competitiveness of Korea's leading firm, this study employed non-parametric approach (based on DEA) with the panel data for 1,900 firms composed of Korea, China and Japan's during the period 2001-2004. Beside of comparing scale of sale and asset, profit, and factor productivity, we measured index of total factor productivity growth and its three components of scale economies, technical efficiency and technical change for these firms. This study suggested valuable points about scale of corporation, investment of corporation, corporation restructuring, improvements of firm's technology and future target for change of industrial structure of Korea's firms.