was a feudal domain under the Tokugawa shogunate of Edo period Japan, located in Mimasaka Province in what is now the northern portion of modern-day Okayama Prefecture. It was centered around Katsuyama Castle which was located in what is now the city of Maniwa, Okayama and was controlled by a cadet branch tozama daimyà  Miura clan throughout all of its history. It was initially known as after the original name of Katsuyama Castle, and in the late Bakumatsu period it was renamed after its location in Mashima County.
In 1764, the fudai daimyà  Miura Akitsugu transferred from Nishio Domain in Mikawa Province to a holding of equivalent kokudaka in Mimasaka Province. He rebuilt Takada Castle and renamed it Katsuyama Castle, and laid out a new jà Âkamachi which became the Katsuyama neighborhood of Maniwa. His son, Miura Noritsugu, encouraged the development of iron mines and iron ore remained a domain monopoly to the end of the Edo Period. The 9th daimyà Â, Miura Hirotsugu, supported the shogunate in the Bakumatsu period, but his son, and final daimyà Â, Miura Takatsugu supported the imperial cause and the clan was later ennobled with the kazoku peerage title of shishaku (viscount).
In 1871 domain became "Mashima Prefecture" due to the abolition of the han system. It was incorporated into Okayama Prefecture via Hojo Prefecture.
As with most domains in the han system, Katsuyama Domain consisted of several discontinuous territories calculated to provide the assigned kokudaka, based on periodic cadastral surveys and projected agricultural yields.