Kangasniemi is a municipality in the province of Eastern Finland and is part of the Southern Savonia region, Finland. The municipality has a population of 5,698 (30 June 2015) and covers an area of 1,326.73 square kilometres (512.25 sq mi) of which 256.86 km (99.17 sq mi) is water. The population density is 5.33 inhabitants per square kilometre (13.8/sq mi).