To provide an optical element capable of obtaining sufficient lightness with a high reflection factor.

This optical element 10 is provided with a reflector 13 having a reflecting plane 13s reflecting incident light 15 and a light transmission element 12 fixed to the reflecting plane 13s of a reflector 13 on an undersurface side. On the top face of the light transmission element, a translucent surface 12s is formed which reflects a part of the incident light 15 and also transmits the other part of the incident light 15. Transparent electrodes 14a, 14b are formed on the top and bottom faces of the light transmission element 12, and the transparent electrodes 14a, 14b are connected to each other with an electric field control circuit 14. When the light transmission element is acted by an electric field, it is changed in thickness t, and a spacing between a plane of reflection 13s of a reflector 13 and the translucent surface 12s of the light transmission element 12 is changed. Wave-length light intensity distribution of interfered reflected light 16 are controlled by using interference between the reflected light 16b by the reflector 13 and the reflected light 16a by the translucent surface 12s.