The concepts of existence and human freedom have been presented by Jean-Paul Sartre in his book entitled Being and Nothingness, and they represent essential parts of his theory. However, Sartre also presents other related concepts, such as bad faith which as been referred to as a device that protects us from the anguish of realising that we are freer than we like to think we are. With this in mind, the purpose of this paper will be to examine why Sartre thought that existence is absurd, as well as the significance of this idea to his view of human freedom.