This paper deals with the class A mandate of the League of Nations, which affected a postwar configuration in the Middle East. It pays attention to a way of making of the system and also demonstrates the final form by treaties between Allied Powers and the Ottoman Empire (Turkey) and by the Mandate for Palestine. It discovers that this system should have originally assisted the new nations to entrench politically in full. However, it also secondarily offers one of the possible views on the origin of the Arab-Israeli problem, which upsets the relation between the west and the Middle East.