Sandsvær is a former municipality in Buskerud county, Norway.
Historically, Sandsvær as a part of Sandsvær og Numedal fogderi had belonged to Akershus amt from 7 February 1685 In 1760 Sandsvær fogderi was moved administratively to Buskerud.
The municipality was created as Kongsberg landdistrikt in 1837. The municipality existed until 1 January 1908, when it was split to form the new municipalities Ytre Sandsvær and Øvre Sandsvær. Prior to the split Sandsvær had a population of 5,709. Both municipalities were later incorporated into Kongsberg.
The Old Norse form of the name was Sandshverfi. The first element is the genitive case of sandr m 'sand', the last element is hverfi n 'district'.