Kanna (神流町, Kanna-machi) is a town located in Tano District of southwestern Gunma Prefecture in the northern Kantō region of Japan. As of February 2015, the town had an estimated population of 2,007 and a population density of 17.5 persons per km². Its total area was 114.6 km². The town has seen a precipitous drop in population, to only one third of its population in 1970, with the remaining population having the second oldest median age in Japan after Nanmoku, Gunma and is thus classified as a Genkai shūraku.