本文旨在比較沙特與馬克思關於人學學說的異同。 沙特認為，每一個重要的歷史時代，都是由能夠捕捉與認識到當代主流之社會和歷史現實的一兩個特出的哲學或世界觀來界定的，在他的心目中，能夠代表現代知識的社會哲學乃是馬克思主義。存在主義，則只是不過是一個生存於時代知識(馬克思主義)邊緣的寄生系統。然而，由於正統馬克思主義(特別是蘇聯的一國社會主義建設)為了保持革命的成果，而在於理論實踐上產生停滯，人成為革命哲學的客體，被賦與一定的角色以滿足於革命哲學的建國目標，馬克思主義已淪落為一種意志主義者的唯心主義。沙特認為，馬克思主義始終以具體的人的生命證成作為其思想的核心，因此，如果要復興馬克思主義，就要正本清源，從重建馬克思主義的人學做起，而有關人存在的意義的探索及是存在主義的主題，這也正是存在主義在此時仍能保有它的獨立性、而未輕易地解消馬克思主義之中的理由。 沙特以存在主義人學對於馬克思人學的補充，符不符合馬克思本人的人學觀，正是本文所嘗試發掘與比較的重點。

　　　　　This paper compares and contrasts the philosophical anthropology of Sartre with Marx. In Sartre's opinion, every significant era in history is characterized by some pre-dominant philosophies or views of the world which enable one to extract and come to know current social and historical realities. According to Sartre, Marxism is a social philosophy which reflects modern knowledge, while existentialism is only a parasitic system which exists on the edge of the modern knowledge that is Marxism. However, because the purpose of orthodox Marxism (especially the Soviet notion of “construction of socialism in one country”) is to maintain the achievements of the revolution, this results in a regression in the practice of the theory. Man becomes an object of revolutionary philosophy and is requested to fill some specific social roles in realizing revolutionary philosophy's goal of state-building. Marxism has already degenerated into a voluntarist idealism. Sartre believes the core of Marxism seeks justification of a concrete lifestyle. Consequently, if we are to recover Marxism, the fundamental method should be to reconstruct Marxist philosophical anthropology. Seeking the meaning of man's being is the task of existentialism. The purpose of this paper is to probe and criticize whether or not Sartre's use of existential philosophical anthropology in supplementing Marxism is consistent with Marx's own view of philosophical anthropology.