Events from the year 1857 in France.

• Monarch – Napoleon III

• 3 March - France and the United Kingdom formally declare war on China in the Second Opium War.
• 27 April - First horse race run at Longchamp Racecourse in Paris.
• 21 June - Legislative election held.
• 5 July - Legislative election held for the second legislature of the French Second Empire.

• 18 April - The Spirits' Book (Le Livre des Esprits in original French), one of The Five Fundamental Works of Spiritism, is published by the French educator Allan Kardec.
• The Flowers of Evil (Les Fleurs du mal in original French), an immensely influential collection of Charles Baudelaire's first poems, is published.

• 4 January - Émile Cohl, caricaturist, cartoonist and animator (died 1938)
• 18 January - Eugène Gley, physiologist and endocrinologist (died 1930)
• 12 February - Eugène Atget, photographer (died 1927)
• 26 February - Émile Coué, psychologist and pharmacist (died 1926)
• 3 March - Alfred Bruneau, composer (died 1934)
• 22 March - Paul Doumer, President of France (assassinated 1932)
• 30 March - Léon Charles Thévenin, telegraph engineer (died 1926)
• 1 June - Le Pétomane (Joseph Pujol), flatulist (died 1945)
• 29 June - Jean-François Klobb, colonial officer (died 1899)
• 10 August - Georges Aaron Bénédite, Egyptologist (died 1926)

• 22 February - Joseph Crétin, first Roman Catholic Bishop of Saint Paul, Minnesota (born 1799)
• 2 May - Alfred de Musset, dramatist, poet and novelist (born 1810)
• 11 May - Eugène François Vidocq, criminal, later first director of Sûreté Nationale (born 1775)
• 17 May - Adolphe Dureau de la Malle, geographer, naturalist, historian and artist (born 1777)
• 23 May - Augustin Louis Cauchy, mathematician (born 1789)
• 30 June - Alcide d'Orbigny, naturalist (born 1802)
• 29 July - Charles Lucien Bonaparte, naturalist and ornithologist (born 1803)
• 3 August - Eugène Sue, novelist (born 1804)^[1]
• 5 September - Auguste Comte, philosopher (born 1798)
• 28 October - Louis-Eugène Cavaignac, General (born 1802)
• 23 December - Achille Devéria, painter and lithographer (born 1800)