[2] Per Japanese census data, the population of Nankan is as shown below The area of Nankan was part of ancient Higo Province, and developed as a post town and barrier gate guarding the northern border Higo from the Nara period.

After the Meiji restoration, the town of Nankan was established with the creation of the modern municipalities system on April 1, 1889.

Nankan has a mayor-council form of government with a directly elected mayor and a unicameral town council of 12 members.

Nankan, collectively with the other municipalities of Tamana District, contributes one member to the Kumamoto Prefectural Assembly.

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