Yes, a part of Catalonia is under French administration.

By the Pyrenees' Treaty (1659) between the king of Castile and the king of France the former gave to France the shire of Rosselló and a half of the shire of Cerdanya. Since them these parts of Catalonia have been included in a French départément and their identity as a part of the Catalan nation has been continuously denied by the French administration. Nevertheless, an important part of the population of these territories have kept their Catalan nationalist feelings and culture.