Lifespan: Unknown to 5/6 of Tenbun 17 (1548)
Rank: bushō, lord of Ikeda Castle
Title: Governor of Chikugo
Father: Ikeda Sadamasa
Siblings: Nobumasa, Hisamasa
Wife: Daughter of Miyoshi Masanaga
Ikeda Nobumasa served as a bushō during the Sengoku period. His common name was Saburō-Gorō and he held the title of Chikugo-no-kami, or Governor of Chikugo. Other names were Katsutoshi and Hisamune. Nobumasa was born as the son of Ikeda Sadamasa. Nobumasa served as the lord of Ikeda Castle in Settsu Province.
During the succession struggle of the Hosokawa clan in the Kinai, Nobumasa’s father, Sadamasa, supported Hosokawa Sumimoto. In 1508, after Sumimoto’s rival, Hosokawa Takakuni, attacked Ikeda Castle, Sadamasa killed himself, so Nobumasa fled. In 1519, Nobumasa acted in coordination with Sumimoto’s rebellion by capturing Shimonotanaka Castle in Settsu and, as a reward, was granted the Teshima District. His subsequent movements are uncertain, but, his role as a commanding officer on behalf of Hosokawa Harumoto appears from the time that Harumoto entered Ikeda Castle. In 1531, Ikeda Castle was felled by Hosokawa Takakuni joined by Uragami Muramune and, in 1533, Harumoto was defeated by the Ikkō-ikki in the Kyōriku-Tenbun Conflict, whereupon he fled to Awaji Province. In 1540, when Kizawa Nagamasa rebelled against Harumoto, Nobumasa served under Miyoshi Nagayoshi (a commanding officer of Harumoto) at the Battle of Taihei Temple.
In 1546, when Hosokawa Ujitsuna and Yusa Naganori raised arms, Nobumasa returned to the service of Ujitsuna. The following year, he surrendered in the wake of an attack by Miyoshi Nagayoshi, but this was not permitted by Harumoto and, on 5/6 of Tenbun 17 (1548) he committed seppuku. Upset with Harumoto’s refusal to accept the surrender of his father, Ikeda Nagamasa (Nobumasa’s son) supported Nagayoshi. Meanwhile, Nagayoshi questioned the role of Miyoshi Masanaga, a member of the same family who was a close associate of Harumoto, demanding an explanation from Harumoto, and after Harumoto refused, betrayed him in favor of Ujitsuna and Naganori and rebelled. This led to the Battle of Eguchi in 1549.