This paper aims to contribute to the research into the philosophy̶in particular, the ethics̶of Arnold Gehlen: one of the most famous representatives of "philosophical anthropology." At the same time, it endeavors to make a contribution, albeit slight, to ethics in general by critically analyzing his ethics. Because the meaning and problems of Gehlen's ethics cannot be fully understood without knowledge of the main point of his philosophical anthropology̶that is, his fundamental view of the human being̶this paper first discusses this view and then proceeds to explore his ethics. In the first part, I explain Gehlen's belief that, unlike all other species, the human being is independent from(almost)all biological instincts and is consequently the totally cultural(non-biological)being. In this part, I also explain that this belief cannot be supported from the perspective of modern biology(evolutionary theory). In the second part, I illuminate that, in contradiction to his fundamental view of man, Gehlen's pluralistic ethics takes biological components into consideration. I demonstrate at the same time that, besides this theoretically problematic contradiction, there are many other problems in his ethics: unclear and inconsistent explanations of four fundamental moral principles, contradictory arguments about the sharp antagonism between the moral principle of institution(state)and the morality of the Enlightenment(which promotes some other moral principles), etc. Finally, I argue that, in spite of all these problems, Gehlen's ethics has at least one advantage over the ethics of philosophers such as Habermas and Honneth, who criticize his ethics on many points: in contrast to the latter ethics, Gehlen's ethics admits and is open to a certain meaning of biological(evolutionary)elements in our social and moral life̶a meaning that seems to be undeniable in light of modern biology(modern evolutionary theory).