Nishiyama (西山町, Nishiyama-machi?) was a town located in Kariwa District, Niigata Prefecture, Japan.
As of 2003, the town had an estimated population of 6,712 and a density of 118.52 persons per km². The total area was 56.63 km².
On May 1, 2005, Nishiyama, along with the town of Takayanagi (also from Kariwa District), was merged into the expanded city of Kashiwazaki.