Gunma Prefecture Tomioka has a Humid continental climate (Köppen Cfa) characterized by warm summers and cold winters with heavy snowfall.

During the Edo period, the area of present-day Tomioka was part of the tenryō territory under the direct control of the Tokugawa shogunate.

It became Tomioka Town within Kitakanra District, Gunma Prefecture on April 1, 1889 with the creation of the modern municipalities system after the Meiji Restoration.

On April 1, 1954, Tomioka annexed the neighboring town of Ichinomiya, and the villages of Ono, Kuroiwa, Takase, and Nukabe, and was raised to city status on November 1, 1958.

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