was a town located in Akaiwa District, Okayama Prefecture, Japan.
Population
As of 2003, the town had an estimated population of 24,939 and a density of 719.95 persons per km<sup>2</sup>. The total area was 34.64 km<sup>2</sup>.
History
On March 7, 2005, San'yō, along with the towns of Akasaka, Kumayama and Yoshii (all from Akaiwa District), were merged to create the city of Akaiwa.