The theme of Augustine’s Eudemonics was the nature of the true happiness and the way to reach the true happiness. He proposed eternity and immutability as the criteria of the true happiness after criticizing Epicurus’ hedonism and stoicism which were based upon materialism. He argued that God is the only origin of the true happiness because God and only God is the eternal and immutable being according to his theory of time. Time and all other beings are created from nothing by God, and therefore temporary and mutable. They should be utilized as means for reaching the true happiness, and should not be mistaken as the ultimate aim. To reach the true happiness one may use his or her own free will to determine his action toward God or things of low order. The caritas which is an orderlylove toward God will bring the true happiness to those who used free will and power of love. On the other hand those who directed their free will and cupiditas, the love toward thing of low order, will meet misery. Therefore, the ultimate responsibility of happiness or misery lies on the right application of each person’s free will. Augustine’s eudemonics is significant as a direction for religious education of the contemporary people whose spirit is overwhelmed by the materialistic abundance.