The present work intends to analyze the concept of multitude and the possibility of thinking it as a political subject in postmodernity, having as reference Spinoza s conception of the term and the contemporaneous interpretations that follows it. The starting point is Antonio Negri s arguments, who observing the forms of power and political organization after 1990s proposes the concept of Empire to explain the politics in contemporaneity and the concept of Multitude as a political subject capable to act in Empire s interior and to construct a democracy in global scale. Next, will be analyzed the references to the term multitudo in Spinoza s own work, paying special attention to the expression quae una veluti mente, contained in Political Treaty. From this expression will be presented the discussion that exists between thinkers like Alexandre Matheron that takes it as reference to sustain that the multitude would be a natural subject, possessing a singular existence; and thinkers like Lee Rice and Den Uyl that criticizes it and defend that the existence of the term quae in the expression was used exactly to differentiate the multitude of a natural subject. Finally, taking as reference the writings of Gilbert Simondon, Etienne Balibar and Paolo Virno, will be articulated the concepts of multitude, trans-individuality and collective individuation to respond critically Antonio Negri proposal and to point out the difficulties in considering the multitude a policital subject.