Pertunmaa is a municipality of Finland located in the province of Eastern Finland which is part of the Southern Savonia region. The municipality has a population of 1,858 (30 June 2015) and covers an area of 454.18 square kilometres (175.36 sq mi) of which 79.7 km (30.8 sq mi) is water. The population density is 4.96 inhabitants per square kilometre (12.8/sq mi).