This paper aims to comprehensively construct human existence and metaphysical aspects in Sartre. In Sartre, humans tend to neglect metaphysical aspects only because of their existence. So, in this paper, I would like to highlight the metaphysical aspect as well as human existence. For Sartre, human existence means the Being-for-itself. This being-for-itself is constituted through reflection as self arises as it first falls from identity to unity. In particular, for Sartre, human consciousness can never be a being like Descartes' cogito, and it is a being that cannot guarantee its own certainty. It exists only as the nihilation of the in-itself, and always causes division with the in-itself because it has a relationship with the in-itself as nothing. To overcome the division is the attempt of identity between the in-itself and the for-itself, and is a problem of metaphysical anthropology. But for Sartre, metaphysical anthropology is an expression of human desire to become a god. However, since the for-itself is in a negative relationship with the in-itself, it cannot truly achieve identity, only unity. Thus, Sartre's view of humanity has a antinomic character in which the existence and metaphysical character are unified a priori, but cannot achieve identity.