On November 3, 2005 Miyajima, along with the town of Ōno, also from Saeki District, was merged into the city of Hatsukaichi.
As of 2003, the town had an estimated population of 2,018 and a density of 66.40 persons per km². The total area was 30.39 km².
In August 2004, both Hatsukaichi and the city of Hiroshima expressed an interest in annexing the town. The people in Miyajima supported Hatsukaichi. A committee for discussing the merger was created as soon as possible and the town was amalgamated with the city of Hatsukaichi on November 3, 2005.