After several decade the nation-state was unable in settle of several issues and problems between states diplomatic negotiation. The International Organization began to appear, changed the nation-state as a primarily actor in political affairs. The ICJ a principal organ of the UN as the biggest International Organizations has believed as the best adjudication way in disputes settlement between states. such as territorial dispute. in line with the title , this undergraduate theis tried to explain about the adjudication process of international Courct of Justice on Pedra Branca between Malaysia and Singapore.