Sovereignty of God and sovereignty of people in the Constitution are not contradictory but it is a two-sided sovereignty, implemented by people through both establishing a political system and every day public life without violating the limited eternal and general religious laws. Hence, the source of popular sovereignty in the Constitution of Islamic Republic is different from the source of sovereignty in both secular and traditional theocratic political systems. In the secular system, sovereignty belongs to people and is implemented by them regardless of God's sovereignty and God's laws and in the theocratic system; God's sovereignty is realized unilaterally, regardless of people's will, by a person who is the direct deputy of God on the earth. Although legitimacy in Islamic republic has two sources, but they are so interpenetrated with each other that realization of each one relies on the other. Because of natural as well as legal god-given freedom of human beings, they can realize their sovereignty on the earth within the framework of God's general ordinances. In return, the sovereignty of God is implemented on the earth only by human being's free will.