Utilitarianism, systematised by Jeremy Bentham (1748-1832) in 18th century, is a theory having strong effects in many different areas from economy and ethics to politic and law especially in England and geopraphies in which anglo-saxon culture reigns. John Stuart Mill (1806 - 1873) reinterpreted Utilitrianism which was inherited from Bentham, in the context of critics of utilitarianism and his own thoughts. In this essay, Mill's utilitarianism will be examined. In this context, I will discuss how his utilitarianism evolved from hedonist position to eudeomonist position. For this purpose, primarily, Mill's utilitarianism will be introduced roughly, then the principle of utility in Mill's utilitarianism, the happiness term developed in the basis of this principle, pleasure, value, freedom, character development, the state, sanction and justice, which have value in the extent to contrubuting the happiness shall be studied.