When applying the current definition of “person who is not principally engaged in finance” of the Banking Act of Korea literally, even CITI group (the owner of the Korea CITI Bank) or SC group (the owner of Korea SC Bank) may be fallen into that category as well as the line star Fund which acquired the Korea Exchange Bank in 2003. This conclusion is very perplexing because CITI group or SC group is well Known international banking organizations.Embarrassed with this conclusion, the financial supervisory authorities announced that they will revise relevant parts of the Banking Act. confronted with this problem, we need to review the whole structure and manner of the Korean regulation restricting ownership of banks. Whether the intent of legislature is well reflected into the Act, or the intent is distorted due to the inappropriate use of legislature techniques, or the Act is unnecessarily hardly written to understand should be reviewed. Originality of the regulation restricting ownership of banks can be attributed to United States of America which has developed the rule of separation of banking and commerce for last 200 years. As a developing country, Korea must have consulted the American rule. However, there are big difference between Korean rule and American rule, which is not a problem by itself, but may be a problem if Korean rule does not provide appropriate answers to questions arising from the regulation. Thus, we need to analyze the problems arising from the Korean regulation on issues of the separation of banking and commerce, and then see how the American rule answer to the questions arising from Korean rule.