As a trait of individual，the explanation of justice as a virtue is full of ambiguity from its initial suggestion by Plato. It is ambiguous whether justice as a virtue primarily applies to individuals or to society. Hume claims that individual justice is an artificial virtue，and tries to explain the source of justice as a virtue in a sentimentalist way. However，his explanation seems not plausible enough and leads to the Humean circle，though he offers some enlightening psychological arguments as complements. The mainstream of contemporary ethics such as that of Rawls thinks that the feelings of individual justice are derived from and developed by living in circumstances of just institutions. In this rationalist way，individual justice is a matter of accepting and conforming to moral and political principles. It is not an explanation of virtue ethics. The theories on stages of moral development in contemporary psychology also suggest explanations of individual justice. One representative explanation is Kohlberg’s theory about six stages of human moral development，whose conclusion is in accordance with that of rationalist ethics. A more significant explanation is offered by Gilligan. Based on a sample of girls，she argues that women tend to think morally in terms of connection to others and in terms of caring about those with whom they are connected. Her study greatly contributes to the rise of contemporary caring ethics，and the explanations of justice as a virtue thus presented，though facing many challenges，is not only better than Hume’s theory on artificial virtues，but also offers a new way to explain justice as a virtue based on virtue ethics.