Six sigma has been the most influential management innovation program since 1996 in Korea. As a result of successful implementation of 6 sigma, there have been a number of dramatic quality improvement cases. However, no empirical study of 6 sigma implementation study has done especially in the service industry of Korea. This article reviews status of finance companies which implemented 6 sigma programs in Korea and then demonstrates the relationship between 6 sigma problem solving tools such as analysis of variance and graph techniques, etc and project success and operational performance. Customer survey tools, process analysis, and documentation tool are identified as influential tools on project success. Tools of measure steps, customer survey tools, and documentation tool are found as influential tools on operational performance.