This study is an empirical study on the relationships among success factors of six sigma(support of top management, education and training, performance-based reward, customer and quality focused thought) on change management activity and business performance. In particular, mediating effect of change management activity on the relationship between success factors of six sigma and business performance is empirically analysed to find causes and impacts among these variables. The study results are as follows: First, there were positive relationships between critical success factors of six sigma(except support of top management) and change management activity. Second, there was also a positive relationship between change management activity and business performance. Third, there were also positive relationships between critical success factors of six sigma and business performance. Finally, change management activity was partial mediating effects on the relationship between critical success factors of six sigma(education and training, performance-based reward, customer and quality focused thought) and business performance. On the other hand, support of top management had no mediating effect on business performance.