Iwakitaira Domain (磐城平藩 Iwakitaira-han?) was a feudal domain under the Tokugawa shogunate of Edo period Japan., based at Iwakitaira Castle in southern Mutsu Province in what is now part of modern-day Iwaki, Fukushima. Its southern neighbor was the Mito Domain which was ruled by the Mito Tokugawa clan, it played the same role of the Iwakitaira Domain is guarding against the powerful Date clan of Sendai Domain. Its northern neighbor was the Nakamura Domain which was ruled by the Sōma clan. The han school was the Shiseidō (施政堂), founded by the Andō clan. The most famous culture created in the Iwakitaira Domain is the Jangara Nembutsu dance.
The southern Hamadōri region of ancient Iwaki Province was ruled by the Iwaki clan from the Heian period through the end of the Sengoku period. However, the clan sided with the western alliance loyal to Toyotomi Hideyori during the Battle of Sekigahara and was dispossessed by Tokugawa Ieyasu, who banished the clan to the minor Kameda Domain in what is now Yurihonjō, Akita. The four districts forming the former territory of the Iwaki clan was given in 1600 as a 100,000 koku domain to Torii Tadamasa, a childhood friend of Ieyasu. Tadamasa changed the kanji of "Iwa" from "岩" to "磐", as he did not feel it was appropriate to continue using the same kanji as the clan which had opposed Ieyasu. Tadamasa constructed a new castle, and laid out a new castle town before being transferred to Yamagata Domain in 1622.