Niwa (丹羽郡 Niwa-gun?) is a district located in Aichi Prefecture, Japan.
As of 2003, the district has an estimated population of 53,576 and a density of 2,163.81 persons per km². The total area is 24.76 km².
Coordinates: 35°20′47″N 136°54′47″E / 35.3465°N 136.913°E