After a unified concept was formed in the report of COSO, the USA, the most developed country in internal control system throughout the world, based on an independent act which is similar to Model Business Corporation Act (MBCA) and SOX Act, expressly stipulated the basic conditions with regard to internal control amid it, thus strengthening internal control. In contrast, there are not perfect legal provisions on internal control for Korean companies. Korean internal control system is only aimed at financial companies; while general companies have the provisions on internal control in External Audit Act and the contents related to financial reports; law-abiding control criterion and compliance officer system were only listed in the amendment of Commercial Law in April 2011. That is to say, internal control system only exists in Commercial Law, Financial Regulation Law, External Audit Act as well as the provisions of financial supervision organ and the laws and regulations of self-discipline supervision organ dispersedly. The laws related to finance have included internal control criterion and compliance officer system. In the amended Commercial Law, compared with compliance officer system, compliance officer system has been strengthened at the level of internal control in accordance with the laws related to finance. Therefore, different from financial enterprises, general enterprises don’t have all-round control system. The internal control system in listed companies hasn’t been introduced uniformly; while the law-abiding control, financial report (accounting) control and publicity control related to law-abiding volunteers are listed in the provisions of Commercial Law, External Audit Act and exchange respectively and have been implemented; as a result, many problems on low efficiency have been caused. So the internal control system which is contained in various laws including law-abiding control system dispersedly must be stipulated uniformly. However, in the short run, current systems shall be maintained for law-abiding supervisors system for financial enterprises as well as internal accounting control system and compliance officer system in External Audit Act. Nevertheless, in the long run, just as internal control system is not implemented additionally for financial enterprises in Japan and the USA, in view of the provisions of Commercial Law in Korea, a unified form is the best for internal control system. But what is more important is that even if internal control system is improved, it can’t be definitely guaranteed, either. We must realize the important fact that we need to provide reasonable guarantee for internal control system. Therefore, even if we have established internal control system, we still need to make long-term efforts to improve internal control while supervising internal control organ.