Despite some stable factors in Iran’s foreign policy , It has changed dramatically toward Israel after the Islamic Revolution in Iran. It was the case while these two countries had intensive strategic military and even economic relations before the Islamic revolution. The main question this article seeks to answer is that among IR theory which of them can better explain this change in Iran’s foreign policy. The article , using the constructivist approach in IR , seeks to show that, constitution Islamic of republic of Iran’s interests and it’s foreign orientations can be traced back to the way Islamic regimes identity is constructed. To this purpose , in the first section , the article looks at constructivism in IR and then examines the role of this approach in foreign policy analyses. Finally the article tries to apply constructivism approach to the analyses of Iran’s foreign policy to Israel.