Nishiyatsushiro (西八代郡 Nishiyatsushiro-gun?) is a district located in Yamanashi Prefecture, Japan.
As of February 1, 2006, the district has an estimated population of 17,878 and a density of 238 persons per km². The total area is 75.07 km².
As of March 1, 2006, the district has only one town left.
Before the Massive mergers of Showa, the east shore of Fujigawa belonged to Nishiyatsushiro District, and the west shore belonged to Minamikoma District.
The district used to have the area of the east shore of Fujikawa, but due to these mergers, the district is now merely the town of Ichikawamisato.
Coordinates: 35°32′28″N 138°30′40″E / 35.5412°N 138.511°E