, also called Okudaira Sadamasa (), was a Japanese daimyō of the Sengoku and early Edo periods. Nobumasa's family considered their origins to have been associated with Mikawa Province. The clan was descended through the Akamatsu from the Murakami-Genji.
Biography
When Nobumasa was born, he was called Okudaira Sadamasa (奥平 貞昌).
Tokugawa allowed Nobumasa to marry his eldest daughter, Kamehime; and he was given Nagashino Castle. Sadamasa was entrusted with the defense of Nagashino Castle by Tokugawa Ieyasu.
Sadamasa's decision to remove himself and his forces from the Takeda supporters became one of the antecedents of the Battle of Nagashino in 1575.
Katsuyori was enraged at Sadamasa's decision to leave the Takeda forces. Nagashino Castle was attacked by Katsuyori with a force of 15,000 troops; but Sadamasa held firm, repelling the Takeda siege until forces of a Tokugawa-Oda alliance eventually arrived to support the beleaguered Okudaira.
Oda Nobunaga was so impressed by the Okudaira's performance in the battle that he offered Sadamasa the honor of adopting part of his name—Nobu. After the battle was won, the hardy warrior was changed from Sadamasa to Nobumasa.
When Nobumasa completed his service as Kyoto shoshidai in 1601, he was transferred to Kanō Domain in Mino Province.