Saruwatari Nobumitsu served as a bushō during the Sengoku and Azuchi-Momoyama periods.  He was a retainer of the Shimazu clan.  He had the title of Palace Guard of the Bureau of Palace Maintenance and later as the Governor of Etchū.

The Saruwatari clan were descendants of Taira no Takamochi from the middle Heian period.

In 1534, Nobumitsu was born as the son of Saruwatari Nobusuke.

Nobumitsu served the Shimazu clan, including as the steward of Kaseda and Hatsuki within the territory governed by the Shimazu.  Nobumitsu excelled in military arts.  He participated in the invasion of Higo Province and, in 1584, the Battle of Okitanawate.  In particular, at this battle, he led 1,000 soldiers out of a total of 6,000 to 8,000 troops from the Shimazu and Arima clans, so he is surmised to have wielded considerable authority as a commanding officer of a battalion, but, according to one source, his son and designated heir, Saruwatari Yajirō, was killed in action.

In 1587, during the Pacification of Kyūshū by Toyotomi Hideyoshi, Nobumitsu was killed at the Battle of Nejirozaka.