To provide a thread and a form for forgery prevention which has high forgery prevention effect using cholesteric liquid crystal and make it easy to make an authenticity decision.

The thread 1 for forgery prevention is a thread used while mixed with the form for forgery prevention, and characterized in that a cholesteric liquid crystal layer 13 which has selective reflectivity at a certain view angle to cause color change is provided on a base material film 11 made of a resin across an adhesive layer 12 or a pattern print of normal printing ink is further provided at a portion on the cholesteric liquid crystal layer and an adhesive layer and protective layer 15 is provided over the entire surface of the liquid crystal layer. This forgery preventive form is obtained by mixing the thread for forgery prevention with base paper.