Nagaoka (長岡郡, Nagaoka-gun) is a district located in Kōchi Prefecture, Japan.
As of 2003, the district has an estimated population of 10,393 and a density of 23.14 persons per km2. The total area is 449.15 km2.
Towns and villages
33°47′31″N 133°40′16″E / 33.792°N 133.671°E / 33.792; 133.671