Niwa Nagatomi (丹羽長富, October 12, 1803 – August 12, 1866) was an Edo period Japanese samurai, and the 9th daimyō of Nihonmatsu Domain in the Tōhoku region of Japan.

[1] Nagatomi, known in his childhood as Kakuzō (覚蔵) and later Bankichi (蕃吉), was born in the clan's Edo residence in 1803.

He encouraged his retainers to excel in both martial and literary arts, and to that end, sponsored the opening of the han school, Keigakukan (敬学館).

He also helped revive the domain's economic situation following a seven-year string of famines during the Tenpō era.

Citing ill health, Nagatomi resigned his positions in 1858, and was succeeded by his sixth son Niwa Nagakuni.