Sarashina (更級郡 Sarashina-gun?) was a district located in Nagano Prefecture, Japan.
As of 2003, the district had an estimated population of 1,467 and a density of 31.99 persons per km². The total area was 45.86 km².
The district had only one village the day before the dissolution.
On January 1, 2005, the village of Ōoka, along with the town of Toyono, and the villages of Togakushi and Kinasa (all from Kamiminochi District), was merged into the expanded city of Nagano. Therefore, Sarashina District was dissolved as a result of this merger.
The villages of Sasai and Imazato were merged to create the village of Kawanakajima (2 towns, 26 villages)