This thesis aims to analyze the concept of terrorism under the impact of international structure. For that purpose, first, the concept of terrorism is compared with other types of violence and its common characteristics were defined. Second, terrorism is classified and historical examples were given accordingly. Third, terrorist organizations were assessed as smart mechanisms that are able to learn and adapt into the conditions in which they subsist. Last, it is highlighted that in the development of terrorist organizations, besides their internal dynamics, states’ tendency to cheat plays a crucial role. Terrorist organizations make use of the feeling of uncertainty and grow stronger out of the states’ rivalry. In the end, they emerge as secondary actors. As units interacting in the international system, the behaviors of terrorist organizations are also shaped and shoved by the structure. They both affect and become subject to the impact of structure. The impacts of the new actor on the international system were evaluated according to the basic principles of Structural Realism. As a result, it is concluded that since structural factors plays a crucial role in the emergence of terrorism, as long as the structure endures, terrorism will also persist. Therefore, states should find ways to coexist with terrorism with the possible least hazard.