Jean Antoine Ernest Constans (1833 - 1913) was a French statesman.

He was born in Béziers. He began his career as professor of law, and in 1876 was elected deputy for Toulouse. He sat in the Left Centre and was one of the 363 of May 16, 1877. Re-elected in October 1877, he joined Freycinet as minister of the interior in May 1880, holding this portfolio until November 14, 1881. On February 22, 1889 he again assumed the same office in the Tirard cabinet.

He became prominent as a stalwart opponent of the Boulangist party, constituting the senate a high court of justice, and taking police measures against the Ligue des patriotes. He resigned on March 1, 1890, but his resignation involved the fall of the cabinet, and he resumed his portfolio in the Freycinet cabinet on March 11.

On December 29, 1889 he had been elected senator by the department of the Haute-Garonne. He was violently attacked by the press and the Boulangist deputies, but did not resign until the whole cabinet withdrew, on February 26, 1892. In December 1898 he was appointed ambassador at Constantinople.