Kozan (甲山町; -cho) was a town located in Sera District, Hiroshima, Japan.
On October 1, 2004 Kōzan, along with the town of Seranishi, also from Sera District, was merged into the expanded town of Sera and no longer exists as an independent municipality.
As of 2003, the town had an estimated population of 6,732 and a density of 67.46 persons per km². The total area was 99.79 km².