Because the health care or medical sector has such characteristics as publicity, professionality, and exclusivity, it cannot be left to the free market system. As a consequence, the state has restricted the establishment of medical institutions in order to protect the life and health of people. Also, the medical law has regulated to permit the establishment of medical institutions by only medical personnel and a few corporate bodies and to ban the establishment of medical institutions under disguised ownership as well as double opening of medical institutions by medical personnel. Nevertheless, there are still many cases that non-medical personnel have dominantly established medical institutions under disguised ownership of other medical personnel or nonprofit corporation. Because they are willing to recover their investment costs as soon as possible, these illegally established medical institutions are likely to make patients undergo unnecessary tests or to perform the excessive treatments and, as a result, are likely to cause infringement on the health and lives of the people. In addition, even if the misconduct is uncovered, the rate at which the costs already paid is very low and, as a result, the damages are straightly connected to the people's loss. On the other hand, there are also increasing number of cases that medical personnel or nonprofit corporations are establishing medical institutions against the medical law regulations. The examples of this illegality are also the double opening of medical institutions and the establishment of medical institutions under disguised ownership by medical personnel or nonprofit corporations. And the damages in these cases may not differ from those in the above cases. In this study, regarding medical law regulations restricting opening a medical institution, I will review the intent of those regulations, the type of violations and criminal punishments, and the possibility of recovery from unlawful profit by the National Health Insurance Act. And then, I would like to find a way for rational improvement of each.