Since 1992, Mongolian law system has been reforming in all areas, such as constitutional law, civil law, criminal law and administrative law. The term “public interest” is unrealized and officially undefined legal term which has reflected 16 laws and 8 constitutional court decisions of Mongolia. Provision 18 of newly-adopted Mongolian administrative procedure law states that the non-governmental organizations and other social organizations may file a claim behalf of the public interest to the administrative court. Realizing the term “public interest” by law is essential to identify the scope of public interest and realize what “public interest” really is.