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

After the Meiji restoration, the town of Kiyama and the villages of Iino, Hiroysu, Fukuda and Tsumori were established with the creation of the modern municipalities system on April 1, 1889.

Mashiki has a mayor-council form of government with a directly elected mayor and a unicameral town council of 18 members.

Mashiki, collectively with the other municipalities of Kamimashiki District contributes two members to the Kumamoto Prefectural Assembly.

In terms of national politics, the town is part of the Kumamoto 3rd district of the lower house of the Diet of Japan.