The present article examines the concept of freedom and its place in the political thought of Isaiah Berlin, one of the leading thinkers of the twentieth century, and Ayatollah Mohammad Hussein Naeini, a great scholar and mujtahid of the constitutional era. The main question of the present article is: What is the place of the concept of freedom in the political philosophy of Berlin and Nain? In answer to this question, the following hypothesis arises: For both Berlin and Nain, freedom and the removal of barriers to freedom lead to human power to decide and the right to choose at both the individual and collective levels. The results show that despite some substantive differences between the Berlin's intellectual system and methodology (secular thinker and disregard for religion) and Naini (mujtahid and religious), the concept of freedom is so important to both that even to explore other important aspects of this thinking. Two thinkers, we must refer to their understanding of this concept. The type of research method in this article is descriptive-analytical and based on library studies.