Iioka, Chiba

 was a town located in Kaijō District, Chiba Prefecture, Japan.
Iioka was a noted port town in the Edo period, and prospered greatly in the aftermath of the Great Fire of Meireki in 1657, as a transshipment center for timber and building materials to Edo.
Modern Iioka was formed on April 1, 1889. On March 31, 1954 it expanded through annexation of the villages of Sangawa and a part of Toyooka.
On July 1, 2005, Iioka, along with the town of Hikata (from Katori District), and the town of Unakami (also from Kaijō District), was merged into the expanded city of Asahi, and thus no longer exists as an independent municipality.
In April 2005 (the last data available before its merger into Asahi), the town had an estimated population of 8,042 and a population density of 600 persons per km². Its total area was 18.27 km².