This work aims at studying the relationship that exists among modernity, rationalization and violence in the book Is this a man?, by Primo Levi. This author is an Italian Jewish, the central character of his book, which consists in the testimony of what he lived in Auschwitz, one of the biggest Nazi concentration camps. In the book, the author recreates, through language, an extra literary world, that of the camp, with its own architecture, its organization and ways of control and extermination. Primo Levi tells the atrocities committed, in a barbaric way, by human beings against other human beings, which makes clear that, when the fight is for survival, ethical and moral values are tested; likewise, in the case of the executioner, true faces are revealed, showing the force of barbarism and its capacity of exceeding all the human limits. Levi tells the facts feeling as if in charge of a moral duty towards the society, the duty of speaking for those who did not survive. Despite the difficulties of representation of his traumatic experience, Levi exposes the whole bureaucratically organized system that made possible that Auschwitz ended up being the horror itself; the place where the instrumentalized reason destroyed the illuminist principles of progress and made men become animals, condemned to a destructive and deadly violence, that was subsidized by the notion of progress and technical development, which were signals of the modernity purposes.