Saji Kazunari (佐治一成?, 1569 - November 16, 1634) was a Japanese samurai warrior of the Sengoku period and Edo period.
He was warden of a castle in a province under the control of Toyotomi Hideyoshi. Hideyoshi caused Kazunari to marry Oeyo, the sister of a favorite concubine. When Kazunari's support for Tokugawa Ieyasu became known, Hideyoshi took back the woman. She later married Ieyasu's son Tokugawa Hidetada and mothered the shogun Tokugawa Iemitsu.
Saji is played by Takehiro Hira in the NHK Taiga drama Gō (2011).