[2] Per Japanese census data,[5] the population of Tsumagoi has recently decreased after several decades of relative stability.

[7] With the creation of the modern municipalities system after the Meiji Restoration on April 1, 1889, the village of Tsumagoi was created within Agatsuma District of Gunma Prefecture.

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

Tsumagoi collectively with the other municipalities in Agatsuma District, contributes two members to the Gunma Prefectural Assembly.

In terms of national politics, the village is part of Gunma 5th district of the lower house of the Diet of Japan.