To provide an optical element capable of making a polarized state regarded as being substantially random.

The directions of lines in respective areas shown in Fig. (a) correspond to the directions of slits. In Fig. (a), the area where the line is not formed is the area where the slit is not formed, and the polarized state is not changed in this area. In the polarized state of emitted light obtained, when linearly polarized light, having the axis of polarization in a direction shown by an arrow in (a), is made incident on the optical element having such structure, each area has the action of a wavelength plate, so that the emitted light is changed to the linearly polarized light, elliptically polarized light and circularly polarized light having a different optical axis direction, as shown in Fig. (b). Thus, when light emitted from the respective areas is collected to one, it includes light having various polarized states, and turns into a light in a state near to random polarized light (non-polarized light) as a whole.