Article is devoted to analysis of relation between international legal theory and philosophy. Author asserts that moral, political and legal philosophy is having a great significance in international legal doctrine. Interaction philosophy and international legal doctrine in modern period of development international law realize in the contest of increasing interdisсiplinary issues. The formation of thoughtful philosophical underpinnigs of international law and his theory have determined of the falling of the positivists dogma. In this article the author argue that international legal theory possess of inherent philosophical foundations. They have been divided into methodological and ideological foundations. Philosophy influences on their development. Author of the article review the philosophical basis of the international legal theory as an object of the philosophy of international law. Separate attention put up analysis of direct and indirect philosophical impact on international legal doctrine. Reason for great significance philosophical ideas is central role of philosophy as a spirits phenomenon of culture. In modern epoch philosophical pluralism is expanding. Diversification of the philosophical conceptions complicates the philosophical basis of international law doctrine. Philosophical basis include idea of oldest philosophers and conception of modern philosophers. Also they include the philosophical views of international lawyers. Author of article suggests to modernize philosophical basis of international law and his doctrine and to establish the mutual consent in the sphere of the philosophical foundations of the international law.