The purpose of this paper is to explore the ground for putting a ban on doping in competitive sport circles, especially focusing on the doping problem as “the issues of that with free will”. The IOC and also some researchers have suggested the reason for prohibiting doping but it's still quite contentious.The object and methods in this paper are as follows: We consider “the issues of doping with free will” (object) in the way of applied ethics with four ethical theories as the framework for researching. The adopted frameworks are as bellow (method).1) the theory of virtue2) the theory of liberalism3) the theory of utilitarianism4) the theory of dutyWe can find some prior views about the topic in terms of the theory of virtue andliberalism, whilethe views based on the theory of utilitarianism and duty are our original one.It would be clarified that the view of virtue doesn't make sense and the view of utilitarianism can only show the prospective judgment. The limit of the theory of liberalism and the significance of the theory of duty would also be shown in this paper as a conclusion.Arguments on the doping issues in terms of the theory of duty, however, are limited on “doping negatively affecting the human body”. It means “doping issues that do no harm to human body in sport” should be treated as different problems that concernwith the essence of sport. Finally, we will suggest that both “the bioethical research” and “the philosophy of sport” should be pursued in the research on doping issues.