Izunagaoka was a town located in Tagata District, Shizuoka Prefecture, Japan in northern Izu Peninsula. As of March 1, 2005, the town had an estimated population of 15,339 and a density of 928.5 persons per km2. The total area was 16.52 km2. The town was served by a station on the Izuhakone Railway. On April 1, 2005, Izunagaoka, along with the towns of Nirayama and Ōhito, was merged to create the city of Izunokuni and thus it no longer exists as an independent municipality.