Iinoo Sadamune served as a bushō during the Sengoku period.  He was a retainer of the Oda clan.  Sadamune served as the lord of Okuda Castle in Nakashima-no-kōri in Owari Province. He founded the Iinoo branch of the Oda clan.

Sademune was either the son of Oda Toshisada and uncle of Oda Nobuhide, or the grandson of Toshisada and cousin of Nobuhide.  However, based on the ages of Toshisada, Sadamune, and Sadamune’s son (Hisakiyo), the latter scenario is more likely.  He became the lord of Okuda Castle and was adopted by the Iinoo clan, dogō, or a powerful local clan who were members of the Shiba clan.

In the sixth month of 1556, upon orders of Oda Nobunaga, Sadamune and his eldest son, Hisakiyo, joined in the attack on Moriyama Castle.  During the Battle of Okehazama, Nobunaga assigned Sadamune, along with Hisakiyo and Oda Hidetoshi (Sadamune’s uncle) to Washizu Castle to defend against the Imagawa army.  On 5/19 of Kōji 2 (1556), Sadamune died as a result of a fierce attack by Asahina Yasuaki and others from the Imagawa army.  Hisakiyo succeeded him as head of the family.

As a direct retainer of the shōgun of the Muromachi bakufu, he may have been a member of the shōbanshū, the shōgun’s personal retinue who managed events at the palace and to accompanied him on visits outside the palace, or this may be confusion with others in the Iinoo clan serving as direct retainers of the bakufu.