The total area of the town was 31.30 square kilometres (12.08 sq mi).. Kagamiishi is located on a plateau with an average elevation of 280 meters in south-central Fukushima prefecture, bordered by the Shakado River to the west and the Abukuma River to the east.

[2] Per Japanese census data,[3] the population of Kagamiishi has plateaued after a long period of growth.

After the Meiji Restoration, it was organized as part of Iwase District in the Nakadōri region of Iwashiro Province.

During the 2011 Tohoku earthquake, over 1000 structures were severely damaged or destroyed, corresponding to approximately 23 percent of the town, The economy of Kagamiishi is primarily agricultural.

The town has one public high school operated by the Fukushima Prefectural Board of Education.