Sartre’s phenomenology has reflections on time since its beginnings, but it has not given rise to a single theory of time. However, it has gone through three different moments, in which a different theory has emerged for each moment. Thus, in relation to the first moment, we find an instantaneous theory; in relation to the second, a theory of temporality; and, finally, in relation to the third, a theory of historicality. For this reason, this paper’s main objective is to explain the intrinsic developments of each theory in order to show how Sartre’s phenomenology contributes to the clarification of one of the most important topics for philosophy, and especially for phenomenology, as is the phenomenon of time.