Niwa clan
Nobunaga placed the castle under the command of Toyotomi Hideyoshi. Hideyoshi in turn transferred power of Iwamura Castle to Tamaru Tomotada. After the Battle of Sekigahara in 1600, it was occupied under Tokugawa rule by the Ogyu Daimyō from 1601 to 1638, by the Niwa clan from 1638 to 1702, and finally by the Ishikawa clan from 1702 until the end of the Tokugawa period in 1868.