Administrative law explains and regulates the relations between the people and the government and supervises the activities related to public services and maintaining public order of administrative organizations. Due to the lack of historical understanding of the concept of "administration" and the laws governing it, the possibility of forming an efficient and coherent administrative law in Iran has been challenged. A review of the course of developments in the administrative system over the past hundred years shows that numerous programs have been implemented to improve it both before and after the revolution. This study, using a descriptive-analytical method, examined the foundations of the development of administrative law in Iran from the Qajar and Pahlavi eras to the developments after the 1979 revolution. By examining the historical course of developments in Iranian administrative law, it is observed that the constitutional period was a turning point in the beginning of the modernization of the country's administrative structure. the principles of separation of powers, government responsibility to the nation, and efforts to create an accountable and transparent system were put forward, but centralization and unaccountable and judicially unsupervised authority of the government still prevailed in the administration of public affairs. After the Islamic Revolution, with the establishment of a new political and social structure, a new system of administrative law was introduced. Emphasis is placed on transparency, government accountability, judicial oversight, and protection of citizen rights in legislation and executive procedures, but the full implementation of these principles in practice faces numerous challenges.