Lifespan: Unknown to 7/29 of Eiroku 6 (1563)
Other Names: Kenmotsu
Lord: Imagawa Yoshimoto
Father: Matsudaira Kiyosada
Siblings: Ietsugu, Bonkōin (wife of Matsudaira Yoshikage)
Children: Tadamasa, Tadayoshi, Tadahiro, daughter (wife of Suganuma Sadamitsu (a daimyō)), daughter (wife of Takeda Jōka, a physician)
Matsudaira Ietsugu served as a bushō during the Sengoku period. He was the third head of the Sakurai-Matsudaira family. The Sakurai-Matsudaira were an illegitimate branch of the Matsudaira clan founded by Matsudaira Nobusada, the second son of Matsudaira Nagachika, the fifth head of the main branch of the Matsudaira clan.
Ietsugu was born as the lineal heir of Matsudaira Kiyosada.
In 1545, at the Battle of Hirokute-nawate, Ietsugu, together with Kiyosada, Sakai Tadanao, and Sakakibara Nagamasa fought against Matsudaira Hirotada, but were defeated. The following year, after Tadanao was pardoned and assigned Ietsugu’s base at Shinano Castle in Owari Province whereupon Ietsugu vacated the premises. In 1553, Ietsugu made an appeal to his lord, Imagawa Yoshimoto, in regard to the territory in Shimowada in Mikawa in a dispute with Matsudaira Tadashige of the Tōjō-Matsudaira family, but, in 1556, this ended in an adverse verdict for Ietsugu. Upon orders of Matsudaira Motoyasu (later known as Tokugawa Ieyasu), Ietsugu successfully repelled the Oda forces attacking Shinano Castle.
In 1563, upon the outbreak of the Mikawa Ikkō-ikki, Ietsugu sided with the ikki forces.,
He died on 7/29 of Eiroku 6 (1563).
According to the diary of Matsudaira Ietada, after the uprising subsided in the second month of 1564, it is noted that Ietsugu was pardoned for being a member of a family of successive generations. Another record raises questions regarding whether he died in 1563, so there is another theory that he died in 1564.