The present invention provides an optical element fixing structure, an optical element fixing body, an optical element and an optical element holder which make tightening with a fixing screw unnecessary, prevents thereby a decrease in performance, such as the generation of strain in the optical element such as a crystal, and can improve the mounting accuracy. The optical element fixing structure 10 includes an optical element 6 and an optical element holder 1 to fix and mount the optical element 6. The optical element 6 has one or multiple slits 8 as strain and stress absorbing means in the thickness direction in the end part thereof, and the optical element holder 1 has depressing means 3 to fix the optical element 6 by depressing at least one of the front surface and the back surface of the optical element 6 outside the slit 8.