If it is the Godfathers who prepared the ground for the christian natural law, it is Thomas Aquinas who closely stipulated the natural law the most in the light of the reality of medieval times.He is not only a theologian but also a philosopher who compiled medieval philosophy. In other words, he complemented “christian philosophy” which was settled into shape by Augustinus, and complied it.Theological and philosophical basics of the principle of Thomas law is based not only on the Ten Commandments and the Law of Moses, especially about the trial in the Book of Deuteronomy, but also on medieval scholasticism founded on the Aristotelian philosophy and Stoicism of Rome, particularly Cicero’s principle of natural law.Thomas’ theological thought is predicated on intellectualism. The natural law is generally an order in accordance with reason. Influenced by Stoicism, he claims that rationality is the sovereign principle of human beings.A man is a rational animal moving toward one’s purpose with free will (conscience and responsibility). Political tendencies of unification and peace is inevitable for humans.He divides the law into eternal law (Lex aerena), natural law (Lex naturale), a man-made law (Lex humana), divine law (Lex divina), and passional law (Lex fomes).By faith, eternal law can be accepted as the guidance ideology of God’s action, which demonstrates God’s plan, and natural law can be found through natural judgements led solely by reason with the help of eternal law saying that a man is a rational creation of God. Also, a man-made law is the positive law enacted by human reason in order to sustain a social order in real life.Believing in that God is present in the world, the Stoic school identifies divine law with natural law. However, the distinct characteristic of Thomas’ natural law is that he separates divine law as a law for afterlife from natural law as a law for this world.More over, he doesn``t argue that the contents of this life is transferred into the next world through harmonious stages. As natural law is mentioned in rationality of the nature, eternal law can be named by such involvement.Thomas contends that any authoritarian state should have an ideal for justice via relative natural law in order to adhere to its own order and peace.This ideal is realized at last when justice properly exchange and distribute everything given.Thomas’ concept of justice is not connected with the strong rejection toward the course of justice, which is abused by authorities and used in distorted ways. In actual practice, demands for justice is just understood as a virtue that should be practiced by a complete object, a nation.In conclusion, although Aquinas more strongly emphasizes pathos in justice than Stoics seeking natural law, he fails to stimulate interest in sharply contrasting the true meaning of law with the positive law. In this way, there is a difference with the modern theory of natural law.