Nitta Kanayama Castle, also known as Kanayama Castle, is a hilltop-style Japanese castle located on Mount Kanayama in Ōta, Gunma Prefecture. Built in 1469 by the Iwamatsu clan, it later came under the control of the Yura clan, who expanded it significantly. Situated between the Tone and Watarase Rivers, the castle was strategically important and withstood numerous attacks by powerful rivals such as Uesugi Kenshin, Takeda Katsuyori, and Satake Yoshishige during the Sengoku period.

The castle was defended successfully for many years, including during a 15-month siege led by the 71-year-old Akai Teruko. In 1590, it was captured by Maeda Toshiie during Toyotomi Hideyoshi's campaign to eliminate the Hōjō clan. After this, the castle was abandoned and fell into ruins. Today, the site is protected as a National Historic Site and is listed as one of Japan's Top 100 Castles.