Yanagisawa Yoshiyasu (Japanese: 柳沢 吉保, December 31, 1658 – December 8, 1714) was a Japanese samurai of the Edo period. He was an official in the Tokugawa shogunate and a favourite of the fifth shōgun, Tokugawa Tsunayoshi. His second concubine was Ogimachi Machiko, a writer and scholar from the noble court who wrote monogatari.