Saijō is a city in Ehime Prefecture, Japan. As of 1 September 2022, the city had an estimated population of 106,016 in 58803 households and a population density of 210 persons per km2. The total area of the city is 509.98 square kilometres (196.90 sq mi).

Ehime Prefecture is a prefecture of Japan located on the island of Shikoku. Ehime Prefecture has a population of 1,334,841 and has a geographic area of 5,676 km2. Ehime Prefecture borders Kagawa Prefecture to the northeast, Tokushima Prefecture to the east, and Kōchi Prefecture to the southeast.