Oyumi Domain (生実藩 Oyumi-han) was a Japanese domain of the Edo period, located in Shimōsa Province (modern-day Chiba Prefecture), Japan. It was centered on what is now Chuo Ward and Midori Ward of the city of Chiba. It was ruled for the entirety of its history by the Morikawa clan.
Oyumi Domain was created in February, 1627, when Morikawa Shigetoshi, a hatamoto in the service of Shogun Tokugawa Hidetada acquired holdings in Sagami, Kazusa and Shimōsa Provinces with revenues exceeding the 10,000 koku necessary to qualify as a daimyō. He was allowed to build a jin'ya on the site of the Sengoku period Oyumi Castle. He later rose to the post of Rōjū and his successors continued to rule Oyumi Domain until the Meiji Restoration.
| # | Name | Tenure | Courtesy title | Court Rank | revenues |
|---|---|---|---|---|---|
| 1 | Morikawa Shigetoshi ( 森川重俊) | 1627–1632 | Dewa-no-kami | Lower 5th (従五位下) | 10 ,000 koku |
| 2 | Morikawa Shigemasa ( 森川重政) | 1632–1663 | Iga-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 3 | Morikawa Shigenobu ( 森川重信) | 1663–1692 | Dewa-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 4 | Morikawa Shigetane ( 森川俊胤) | 1692–1732 | Dewa-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 5 | Morikawa Shigetsune ( 森川俊常) | 1732–1734 | Naizen-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 6 | Morikawa Shigenori ( 森川俊令) | 1734–1764 | Naizen-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 7 | Morikawa Shigetaka ( 森川俊孝) | 1764–1788 | Kii-no-kami | Lower 5th (従五位下) | 10 ,000 koku |
| 8 | Morikawa Shigetomo ( 森川俊知) | 1788–1838 | Naizen-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 9 | Morikawa Shigetami ( 森川俊民) | 1838–1855 | Dewa-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 10 | Morikawa Shigehira ( 森川俊位) | 1855–1858 | Dewa-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 11 | Morikawa Shigenori ( 森川俊徳) | 1858–1862 | Dewa-no-kami | Lower 5th (従五位下) | 10,000 koku |
| 12 | Morikawa Shigekata ( 森川俊方) | 1862–1871 | Naizen-no-kami | Lower 5th (従五位下) | 10,000 koku |
The site of the Oyumi Domain jin'ya is now under a residential area of the city of Chiba.