The purpose of the study is to analyze the concept of the Natural Right in the late 18th century in terms of founding American empire. The ideology to expand national territory often justified its means in asserting national defense, the struggle for eccological existence, and God's Providence & Natural Will etc. The ideology also contains quasi-scientific law based upon social Darwinism or racism. Historically, each phase of the ideologies have developed its own set of doctrines that have caused territorial aggrandizement to appear either as the inevitable working of Providence or as the dictate of the highest international morality. Such arguments often reflect a virtual image that U.S. diplomacy points international justice, and legal legitimacy and moral supremacy. However one sure that those ideologies in reality were obviously hypocritical or rhetorical devices.