PROBLEM TO BE SOLVED: To provide a novel reflector as a reflector for insect proof, and an insect proof system and an insect proof method for highly general purposes.SOLUTION: An insect proof system comprises: a reflector for insect proof reflects a light of a wavelength region of 570 to 620 nm wavelength-selectively, in which the reflectance of said reflection is a circular polarization said reflector and an irradiation device. An insect proof method comprises: irradiating said reflector arranged in the entrance or window of a building with a light having a wavelength of 570 to 620 nm, thereby to prevent an insect from intruding into said building.SELECTED DRAWING: None