In recent decades, many of rules, principles, and procedures which dominates the interactions of international actors have changed dramatically due to a transition from Westphalian order to post Westphalian order in the world system. In response to the changes in global arena, new diplomacy has emerged with different forms like media diplomacy, public diplomacy, track two diplomacy and virtual diplomacy. Understanding the reasons for the emergence of new diplomacy is very important and can be influential in determining foreign policy’s course of action. This article tries to investigate the reasons of the emergence of new diplomacy in the changing world system and proposes three factors as a hypothesis: declining of the role of sovereign states as a consequence of the growth of non-governmental actors, remarkable advancements in information and communication technologies and the enhancement of public opinion status. The results of this article can offer guidelines for directing foreign policy.