Ishikawa Kazumasa (石川 数正, 1534–1609) was a Japanese notable retainer under Tokugawa Ieyasu, who served him since childhood, when they were both hostages under the Imagawa in 1551.

By 1567, the majority of daimyō forces in the Tokugawa armies were organized in two divisions, each with a separate commander.

Later, Kazumasa and Sakakibara Yasumasa accordingly issued statements attacking Hideyoshi, due to the Tokugawa's decision.

After Hideyoshi's death, and the establishment of Tokugawa Shogunate, Kazumasa and his family were punished by being deprived of their fief.

Kazumasa then later decided to retire and live with his son Ishikawa Yasunaga, until he died in 1609.