In studies of Islamic civilization, "Commander of the Faithful," is one of the most important and frequently used words. It is generally referred to someone who has the political leadership of the Muslim community. Did it mean the same at the beginning or change has happened in its meaning? Did it have any particular meaning or did it emerge by the passage of time and the needs of the Islamic community? These issues have always been at the center of attention.  Apart from the ideological theories, with a scientific approach this article tries to examine its position over time with the assumption that despite its religious origin, under the rule of the Islamic government, this word has adopted a political meaning which has even been cited and approved by the Imams. Soon it adopted a third meaning, however they are close in terms of concept.