The expression ¿informal economy¿ encompasses a huge diversity of situations and phenomena. Indeed, the informal economy manifests itself in a variety of forms across and within economies. Formalization process and measures aiming to facilitate transitions to formality need to be tailored to specific circumstances that different countries and categories of economic units or workers face. The informal economy in Algeria has emerged spectacularly, to be stuck as an almost important element in the economic and social landscape, and this is under the cumulative influence of terrible internal factors and globalization imposed by the lack of adequate preparation for its repercussions on our country. So, through this presentation, we have clearly demonstrated the great contradiction between sustainable development and the informal economy, both in the conceptual and the practical terms.