Tundzha Municipality (Bulgarian: община Тунджа) is a municipality of Yambol Province, southeastern Bulgaria. The municipality has an area of 1,218.86 square kilometres, making it the second-largest by area in the country after the Capital Municipality (i.e. the city of Sofia). It covers 44 villages and has a population of 27,225 according to 2005 data. All the villages in the province are administratively equal, and the administrative centre of the municipality is located in the provincial capital of Yambol, which is not part of Tundzha municipality itself: the city is equivalent to Yambol municipality, which is an enclave within Tundzha municipality.