| Iioka | |
| Native Name Lang: | ja |
| Settlement Type: | Former municipality |
| Seal Type: | Emblem |
| Pushpin Map: | Japan |
| Pushpin Map Caption: | Location in Japan |
| Coordinates: | 35.7°N 183°W |
| Subdivision Type: | Country |
| Subdivision Name: | Japan |
| Subdivision Type1: | Region |
| Subdivision Name1: | Kantō |
| Subdivision Type2: | Prefecture |
| Subdivision Name2: | Chiba Prefecture |
| Subdivision Type3: | District |
| Subdivision Name3: | Kaijō |
| Extinct Title: | Merged |
| Extinct Date: | July 1, 2005 (now part of Asahi) |
| Leader Title: | Mayor |
| Leader Title1: | Vice Mayor |
| Unit Pref: | Metric |
| Area Total Km2: | 18.27 |
| Population Total: | 10,954 |
| Population As Of: | April 2005 |
| Population Density Km2: | 600 |
| Timezone1: | JST |
| Utc Offset1: | +09:00 |
| Blank Name Sec1: | City hall address |
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 was merged with the city of Asahi, the town of Hikata (from Katori District), and the town of Unakami (also from Kaijō District) to form the new Asahi city,[1] and it disappeared.
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.