Genkai (玄海町, Genkai-chō) is a town located in Higashimatsuura District, Saga Prefecture, Japan.

Saga Prefecture Genkai has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

Following the Meiji restoration, the villages of Chika and Ariura, were established with the creation of the modern municipalities system.

Genkai originally planned to merge into Karatsu with the rest of the district, but was concerned about the slow administrative response of the surrounding areas.

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

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