Niiro Tadamoto (新納 忠元, 1526 – 16 January 1611) was a retainer of Satsuma daimyō Shimazu Yoshihisa.

Tadamoto was a skilled samurai called Oni Musashi.

[1] Tadamoto had an active role at the Battle of Kizaki (1572), and, in 1574, became a hostage to compel the surrender of an enemy commander who had held-out in Ushine Castle for over one year.

Tadamoto joined in the Siege of Minamata Castle (1581), and at the Battle of Okitanawate (1584).

At the Battle of Sendaigawa,[2] Niiro led his men in a charge against the Toyotomi force, and even engaged the famous warrior Katō Kiyomasa in personal combat before retreating under cover of night.