Masku is a municipality of Finland, located in the province of Western Finland and part of the Southwest Finland region. It lies about 17 kilometres (11 mi) just north of Turku.
The municipality covers an area of 204.01 square kilometres (78.77 sq mi), of which 29.21 km2 (11.28 sq mi) is water. Its population is 9,612 (31 December 2025), giving a population density of 54.96 inhabitants per square kilometre (142.3/sq mi).