Piuro is a comune (municipality) in the Province of Sondrio in the Italian region Lombardy, located about 100 kilometres (62 mi) north of Milan and about 40 kilometres (25 mi) northwest of Sondrio, on the border with Switzerland. As of 31 December 2004, it had a population of 1,938 and an area of 85.4 square kilometres (33.0 sq mi).