Aioi is a city in Hyōgo Prefecture, Japan. As of 31 May 2022, the city had an estimated population of 28,208 in 13143 households and a population density of 310 persons per km2. The total area of the city is 90.4 square kilometres (34.9 sq mi).

Hyōgo Prefecture is a prefecture of Japan located in the Kansai region of Honshu. Hyōgo Prefecture has a population of 5,469,762 and a geographic area of 8,400 square kilometres. Hyōgo Prefecture borders Kyoto Prefecture to the east, Osaka Prefecture to the southeast, and Okayama and Tottori prefectures to the west.