Niwa Nagashige (丹羽 長重^?, May 11, 1571 - April 30, 1637) was a Japanese daimyo who served the Oda clan. Nagashige was the eldest son of Niwa Nagahide and married an adopted daughter of Oda Nobunaga. He took part in his first campaign in 1583, assisting his father in the battles against Shibata Katsuie. In the Battle of Nagakute, at the age of thirteen, Nagashige led a troop of Niwa clan in the place of his father, who was ill.

In 1585, upon Nagahide's death, Nagashige received his father's fief of 1,230,000 koku (spanning Echizen, Wakasa, and parts of Kaga). This is believed to have been Hideyoshi's effort to reduce the Niwa clan's strength.

In 1600, at the Battle of Sekigahara, Nagashige took part in Ishida Mitsunari's force and fought against Maeda Toshinaga of Kaga; he consequently had his holdings briefly confiscated. His daimyo status was restored in 1603, when the Tokugawa family granted him 10,000 koku at Futsuto, in Hitachi Province. At the siege of Osaka from 1614 to 1615, Nagashige fought on Tokugawa Ieyasu's side. For his service in battle, he had his stipend increased; his fief was transferred to the Edosaki Domain (20,000 koku).

Nagashige was promoted again in 1622 with a move to the Tanakura Domain and a stipend increase to 50,000 koku. His rise culminated in 1627, when he was granted the Shirakawa Domain (worth 100,700 koku) and built Shirakawa Castle.

Nagashige's successor was his son, Mitsushige.