Niwa Nagaakira (丹羽長祥, November 18, 1780 – September 19, 1813) was an Edo period Japanese samurai, and the 8th daimyō of Nihonmatsu Domain in the Tōhoku region of Japan.

[1] Nagaakira, first known by his childhood name of Nabetarō (鍋太郎), was the eldest son of Niwa Nagayoshi by a concubine.

Relying on his reformist karō Narita Yoriyasu (成田頼綏), he encouraged agriculture, promoted education, and assisted in the development of special crafts amongst the commoners.

It was at this point that Nihonmatsu's famed Banko-yaki (二本松万古焼) glazed pottery, Kawasaki paper (川崎の紙), Hiraishi tatami (平石の畳), and Ōhira kushikaki (大平串柿; skewered persimmons) were originated.

[2] Despite these reforms, the domain's finances were hard pressed due to natural disasters and other unforeseen events, as well as the shogunate's request for monetary and construction assistance on flood control projects.