In The Second Sex, Simone de Beauvoir carries out an analysis of gender. Although her discourse focuses mainly on the feminine gender, she provides interesting tools to explore the features of masculinity. Our purpose is to reappraise this conception of masculinity in Beauvoir's thought, in order to improve our vision of the feminist claims. We will find the main characteristics that Beauvoir associates to masculinity: being a man is being-for-itself and trascendence, is characterised by his ability to use violence and make war, finally, he is able to objectify other subjects. We will conclude with a criticism of this charactertization.