The city area has an elongated shape from east to west along the Tainai River basin.

Tainai has a Humid climate (Köppen Cfa) characterized by warm, wet summers and cold winters with heavy snowfall.

Tainai has a mayor-council form of government with a directly elected mayor and a unicameral city legislature of 14 members.

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

The city has one public high school operated by the Niigata Prefectural Board of Education.