The article contains an analysis of the reasons and foundations for the Islamic Revolution Guards Corps (IRGC) appearance in the Islamic Republic of Iran. The author sheds light on the process of the IRGC development and its current state. For almost 40 years of its existence, IRGC has transformed from a set of ill-armed and weak organized groups, functioning mainly as the guarding structures, to a unique governmental structure. For now, the set of IRGC`s functions includes such spheres as military, police and gendarme, and religious sphere (which includes “special operations”). IRGC also bears some political and financial-economic functions, among which ensuring internal security of the Islamic regime in the Islamic republic of Iran by struggling with political opposition; suppression of anti-governmental demonstrations; control for the political, civil and nongovernmental organizations, private companies and firms; defense from political aggression from outside; making reconnaissance and counterespionage; prevention the country from the Western ideological and cultural flows; management of the resistance forces “Basij” and civil defense; monitoring the compliance by citizens the Islamic life and moral norms; implementation of the conception of the “Islamic Revolution export”; fighting drug-related business and banditry; participation in the state borders` defense actions (if required); involvement in large-scale governmental economic projects. In military terms, the IRGC has such military troops as land forces, air and naval forces, resistance forces “Basij” and Special Forces “Qods”. The IRGC is a high-class component of the military forces in the Islamic republic of Iran, which includes an Army itself. However, the range of the IRGC commitments is much broader than standard military ones. Thus, nowadays, the IRGC plays a significant role in politics (both internal and external) and fulfils special tasks outside of the IRI. Having large financial and economic assets, the IRGC controls from 25% to 35% of the Iran`s economics. Today the IRGC exists as a corporate union of the military, intelligence, police and gendarme, political, ideological, economic and financial structures of the modern Iran. In fact, the IRGC is a cross-functional mega holding, leading by the Supreme leader and his surroundings. Modern IRGC is the essential foundation for the IRI`s statehood, it is a state within a state.