To provide an illuminator capable of realizing uniform illumination without causing an interference pattern even in using a high-luminance laser as a light source.

The illuminator is equipped with a fly-eye lens 5 constituted of a plurality of lenses 9 on an irradiation optical axis 2, and parallel luminous flux are made incident on the fly-eye lens and divided by the lenses. A plurality of optical fibers 12 having different length are disposed in a state where the respective incident ends are made to face to the emitting ends of the lenses, and the emitting ends of the optical fibers are arranged at or near the incident side focus of a condensing lens 6. The divided luminous flux emitted from the respective optical fibers are superposed on a body to be irradiated for irradiation by the condensing lens.