Crostau (Sorbian Chróstawa) is a village and former municipality in Upper Lusatia in the Bautzen district of eastern Saxony in Germany.

With the big German settlement in the 10th up to the 12th century an older place was transformed into the small castle, called "Kroste".

In 1352, the castle was destroyed by the "Six-cities-alliance" of Upper Lusatia, which was the first time Crostau was mentioned in a written work.

Since German reunification, the CDU (conservative party) has been the leading political force in the community.

Crostau is far from the important highways of the region and has no industry, but it is linked to tourist routes and has beautiful surroundings.