Bad Buchau (  ) (formerly Buchau) is a small town in the district of Biberach, Baden-Württemberg, Germany with about 4,000 inhabitants. It is situated near Lake Federsee, which is separated from the town by a wide reed belt.

Bad Buchau incorporates the nine villages of Allmannsweiler, Dürnau, Kanzach, Betzenweiler, Moosburg, Alleshausen, Seekirch, Tiefenbach, and Oggelshausen, as well as the outlying farm settlements of Ottobeurer Hof, Bruckhof, and Henauhof. Also part of Bad Buchau is the formerly independent district of Kappel.