To effectively prevent a forgery by a color copier or the like by immediately identifying the presence or absence of the copy using the copier or the like.
The printed product is obtained by pair printing a design by using a brown ink 2 and a green ink 3 having different hues on a base material 1. This product is constituted of a pattern looking remarkably different hues but in the case of copying the product by a color copier, a part printed by the brown ink is changed to a yellowish green having an entirely different hue, and a part printed by the green ink is changed to the yellowish green to be homochromatic with the previous yellowish green so that the patterns of the both cannot be recognized. This copy preventive product has an extremely large contrast of the hues of the product and the copy as compared with prior art, and hence the presence or absence of the forgery can be easily identified.
NAGAI YOSHIAKI
TAKAYAMA SUEHIKO
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