Аннотация:The purpose of this work is to study the international legal instruments related to the definition of terrorism. Method: historical and legal analysis, deductive and inductive methods. The article deals with the actual problems related to the definition of terrorism in international law. Thus, the authors pay special attention to the international legal norms provided for in the Convention on the Prevention and Punishment of Terrorism (1934), the Geneva Convention on the Suppression of Terrorism (1937), the Convention on the Suppression of Terrorism (1972), the Convention on Prevention and punishment of crimes against internationally protected persons, including diplomatic agents (1973) and etc. The authors come to the conclusion that international law has not developed a General concept of terrorism, which creates certain difficulties in the implementation of the norms of international law in the internal national state of modern states.