The line parallels the coast of Shimabara Peninsula, Nagasaki Prefecture.

The Shimabara Railway Co. opened the Isahaya – Aino section in 1911, extending the line to Kojiromachi in 1912 and Minami-Shimabara the following year.

The Kuchinotsu Railway Co. opened the Minami-Shimabara – Dozaki section in 1922, extending the line to Harajo in 1926 and Kazusa two years later.

In 1993 a major lava flow forced the closure of the line between Shimabarakō and Fukae, and services did not resume on that section until 1997.

The Shimabarakō – Kazusa section was closed on 1 April 2008 owing to declining patronage.