Santō (三島郡 Santō-gun?) is a district located in Niigata Prefecture, Japan.
After two successful mergers with Nagaoka during an eight-month period, the district has an estimated population of 5,565 and a density of 125.39 persons per km². The total area is 44.38 km².
Coordinates: 37°31′45″N 138°42′22″E / 37.5291°N 138.706°E