For the success of Happiness Education, its foundation must be solidly established by a theoretical approach from various academic fields before implementing it. The purpose of this research is to study what the essence of Happiness Education must be, based on Aristotle’s Theory of Happiness on the philosophical level. To achieve this purpose, this research has dealt with not only Aristotle’s Theory but also other ancient and modern philosophers’ opinions. By this, this research has clarified what many philosophers commonly said: that an ethical life leads one to happiness. If the essential way to happiness is an ethical life, the essence of the Happiness Education must also be Character Education which would teach one to have moral character. Furthermore, this research deeply studied Aristotle’s theory of Happiness, and therefore suggests various implications that Aristotle’s thought gives to Happiness Education and the desirable direction of Character Education for Character Education. Through this, the conclusion that Character Education, which would help students have the right virtues and understand social relationships, is necessary for the success of Happiness Education was induced.