John Finnis is well-known as a natural law theorist who reconstructs Thomas Aquinas’s natural law theory of morality. Moreover, Finnis applies Aquinas’s discourses on personal identity to the interpretation of All’s Well That Ends Well, one of William Shakespeare’s problem plays. Modern lawyers, who analyze the concepts of the provision of laws, claim that natural law exists in a form like the provisions of laws. However, modern natural law depends less on the form of provisions of laws than on a theory that examines the moral principles of human actions. Hence, following a tradition that regards the law as an external principle on human actions, natural law is grounded on the same criteria for assessing the legality and legitimacy of law as the principle of morality on human actions. Finnis demonstrates All’s Well That Ends Well as an example of Aquinas’s theory of personal identity and provides a new perspective on the comedy. More precisely, Finnis’s concept of the Four Orders (nature, thought, choice, and culture) that determine the uniqueness of personal identity helps us to tackle the difficulties in understanding the last scene of the play. This paper not only introduces Finnis’s discussion on the characteristics of natural law theory but also evaluates his application of the natural law theory to Shakespeare’s play. In light of the legal difference between England and France, it is the gap between the French court and the English audience that renders All’s Well That Ends Well comical and hilarious.