Mishima (三島町; -machi) was a town located in Santō District, Niigata, Japan.
As of 2003, the town has an estimated population of 7,535 and a density of 206.61 persons per km². The total area is 36.47 km².
On April 1, 2005 Mishima, along with the town of Oguni, from Kariwa District, the village of Yamakoshi, from Koshi District, the town of Nakanoshima, from Minamikanbara District, and the town of Koshiji, from Santō District, was absorbed into the city of Nagaoka.