| Native Name: | 岩村田藩 |
| Conventional Long Name: | Iwamurada Domain |
| Common Name: | Iwamurada Domain |
| Subdivision: | Han |
| Status Text: | under Tokugawa shogunate Japan |
| Government Type: | Daimyō |
| Today: | Nagano Prefecture |
| Year Start: | 1703 |
| Year End: | 1871 |
| Era: | Edo period |
was a feudal domain under the Tokugawa shogunate of Edo period Japan. It is located in Shinano Province, Honshū. The domain was centered at Iwamurada Jin’ya, located in what is now part of the city of Saku in Nagano Prefecture.[1] It was ruled for all of its history by a junior branch of the Naitō clan.
In 1703, Naito Masatomo, the daimyō of Akanuma Domain in Musashi Province exchanged his scattered holdings in Musashi, Kōzuke, Hitachi, Kazusa and Shimōsa Provinces for a holding consisting of 27 villages with an assessed kokudaka of 16,000 koku in Saku District in Shinano Province. This marked the start of Iwamurada Domain, which his descendants continued to rule uninterrupted until the Meiji restoration.
The 6th daimyō, Naito Masatsuna, was a brother of Mizuno Tadakuni and served as a rōjū in the administration of the Tokugawa shogunate. During his time, the status of the domain was upgraded to that of a “castle-holding domain”, although no castle was actually built.
During the Boshin War, the domain quickly supported the imperial side, and participated in the Battle of Utsunomiya Castle and Battle of Hokuetsu and Battle of Aizu. In July 1871, with the abolition of the han system, Iwamurada Domain briefly became Iwamurada Prefecture, and was merged into the newly created Nagano Prefecture. Under the new Meiji government, Naitō Masanobu, the last daimyō of Iwamurada Domain was given the kazoku peerage title of shishaku (viscount).
As with most domains in the han system, Iwamurada Domain consisted of several discontinuous territories calculated to provide the assigned kokudaka, based on periodic cadastral surveys and projected agricultural yields.[2] [3]
| Name | Tenure | Courtesy title | Court Rank | kokudaka | Notes | |
| Naitō clan (fudai) 1703-1871 | ||||||
| 1 | 1703-1711 | Shikibu-shōyu (式部少輔) | Lower 5th (従五位下) | 16,000 koku | transfer from Akanuma Domain | |
| 2 | 1711-1746 | Shimōsa-no-kami (下総守) | Lower 5th (従五位下) | 16,000 koku | ||
| 3 | 1746-1770 | Mino-no-kami (美濃守) | Lower 5th (従五位下) | 16,000->15,000 koku | ||
| 4 | 1770-1792 | Shima-no-kami (志摩守) | Lower 5th (従五位下) | 15,000 koku | ||
| 5 | 1792-1802 | Mino-no-kami (美濃守) | Lower 5th (従五位下) | 15,000 koku | ||
| 6 | 1802-1860 | Bungo-no-kami (豊後守) | Lower 5th (従五位下) | 15,000 koku | ||
| 7 | 1860-1871 | Shima-no-kami (志摩守) | Lower 5th (従五位下) | 15,000 koku | ||