This study aims to take stock of Jean-Paul Sartre's criticism of imperialism, colonialism and neo-colonialism as they relate to the Third World in general, and Africa in particular. To sum up, through our choice of author and subject, we would like to assert once again that the unity of the African continent is the surest way to its liberation. This path to unity offers effective means for Africa's economic, political and cultural development. Our reflection does not consist in a simple analysis of the history of colonization, as a historian would do. In the first part, we use historical analysis to show, with Sartre, that colonialism is a system of domination and alienation of both the colonized and the colonizers. In the second part, we'll look at our independence and the causes of neo-colonialism. Finally, the third part will define the prospects for African liberation.