To miniaturize an illuminator to be used for an image sensor, and to uniformly illuminate the surface of a subject while using a more inexpensive light source.

Plural light source means (small light sources such as LED) 4 for illuminating a subject 7 are provided around an optical path guide 5 and arranged so as to emit light parallel to the surface of the object 7 and a light diffusion plane 6 of a chevron shaped projecting pattern or the ruggedness pattern such as a rectangular pyramid is provided on the inside surface of the optical path guide 5 prepared by acrylic or the like. Thus, the nonuniformity of illumination is reduced, the entire device can be miniaturized and the cost is decreased as well.