Niwa Nagashige (丹羽長重; May 11, 1571 - April 1, 1637) is a daimyo and retainer of Oda clan.

Nagashige is the eldest son of Niwa Nagahide and married an adopted daughter of Oda Nobunaga.

On 1583, Nagashige fought together with his father for battles against Shibata Katsuie. On the battle of Nagakute, at the age of thirteen, Nagashige led troop of Niwa clan in the place of his father.

But on 1585 after Nagahide died, Hashiba Hideyoshi reduced his domain to barely 40,000 koku at Matsuto, Kaga Province from over a million and took away Echizen Province and Wakasa Province. This is believed to have been Hideyoshi's effort to reduce Niwa clan's strength.

On 1600 at the battle of Sekigahara, Nagashige took part in Ishida Mitsunari's force and fought against Maeda Toshinaga. At the siege of Osaka from 1614 to 1615, Nagashige fought on Tokugawa Ieyasu's side. He had some success and had his domain increased and moved to current day Shirakawa, Fukushima and became the first ruler of Shirakawa Han.