Kaisō (海草郡 Kaisō-gun?) is a district located in Wakayama Prefecture, Japan.
As of September 1, 2008, the district has an estimated Population of 10,988 and a Density of 85.6 persons/km². The total area is 128.31 km².
Coordinates: 34°09′14″N 135°23′35″E / 34.154°N 135.393°E