Ienaga is both a Japanese surname (written: , ) and a masculine Japanese given name (written: ). Notable people with the name include:
Last name Akihiro Ienaga (born 1986), Japanese footballer Saburō Ienaga (1913–2002), Japanese historian
First name Minamoto no Ienaga (1170 – 1234), Japanese waka poet Naitō Ienaga (1546–1600), Japanese samurai Ikoma Ienaga (died 1607), Japanese samurai