The Salon de Mai (the May salon) is a French group of artists which formed in a café in place du Palais Royal in Paris in October 1943 during the German occupation of France. It was founded in opposition to Nazi ideology and its condemnation of degenerate art. It founder members were the art critic Gaston Diehl and the painters, sculptors and engravers Henri-Georges Adam, Emmanuel Auricoste, Lucien Coutaud, Robert Couturier, Jacques Despierre (who suggested naming the salon after the month in which its first meetings were held), Marcel Gili, Léon Gischia, Francis Gruber, Jean Le Moal, Alfred Manessier, André Marchand, Edouard Pignon, Gustave Singier, Claude Venard and Roger Vieillard, who together formed it direction committee. Many among them (Coutaud, Gischia, Le Moal, Manessier, Marchand, Pignon, Singier) participated in the 1941 exhibition "Vingt jeunes peintres de tradition française".
Under its president Gaston Diehl the first Salon de Mai exhibition took place in the galerie Pierre Maurs (3, avenue Matignon) on 29 May to 29 June 1945. Its honorary committee was made up of Germain Bazin, Jacques Dupont, René Huyghe, Bernard Dorival, Michel Florisoone, Pierre Ladoué and Marc Thiboutet. Its judging panel was headed by Jean Follain. The catalogue of this first Salon had a preface by Gaston Diehl, with texts by René Bertelé and André Rolland de Renéville, poems by Jacques Prévert, Lucien Becker, André Frénaud, Jean Follain and Guillevic.
Gaston Diehl was president of the Salon de Mai until 1997.