Atsumi (渥美郡, Atsumi-gun) was a rural district located in southern Aichi Prefecture, Japan, located on the Atsumi Peninsula in Mikawa Bay. As a result of various consolidations and mergers of municipalities, the district was incorporated into the cities of Toyohashi and Tahara in 2005. As of 2004 (the last data available before its dissolution), the district had an estimated population of 21,657 and a population density of 263.5 persons per km2. Its total area was 82.18 km2.