Kaminoseki (上関町, Kaminoseki-chō) is a town located in Kumage District, Yamaguchi Prefecture, Japan.

During the Edo Period, the area was part of the holdings of Chōshū Domain and prospered as a port for the kitamaebune coastal trade.

Following the Meiji restoration, the village of Kaminoseki within Kumage District, Yamaguchi was established with the creation of the modern municipalities system on April 1, 1889.

Kaminoseki has a mayor-council form of government with a directly elected mayor and a unicameral town council of ten members.

In terms of national politics, the town is part of the Yamaguchi 2nd district of the lower house of the Diet of Japan.