Thread and method of manufacturing the same, counterfeit preventive paper using thread, counterfeit preventive printed material, and method of judging authenticity utilizing them

A counterfeit preventive paper, comprising:

• paper sheets to be made in the counterfeit preventive paper;
• and
• a thread inserted into the paper sheets so as not to be directly viewed from either surface of the counterfeit preventive paper, the thread comprising a string-like and light permeable substrate having front and back sides, at least one metal thin film layer formed in patterns of either character or figure or both on both sides of the substrate, and a colored resin layer on the exterior of the metal thin film layer formed in patterns that are patterned same as the metal thin film layer, the patterns made of the metal thin film layer and the patterns of the colored resin layer formed thereon being separated from each other,
• wherein the paper satisfies the following conditions (a) and (b):
• (a) when the colored resin layer can be recognized as the pattern by reflected light, if the paper is viewed from an opposite side with reflected light, the laterally or vertically inverted pattern of the recognized colored resin layer is hardly visible, and
• (b) if the paper is viewed with transmitted light while held to light, the pattern of the recognized colored resin layer is visible as a shadow.