Data carrier with liquid crystal secret protective element

PURPOSE: To prevent a forgery by using a liquid crystal polymer existing as a solid at the room temperature in a form of oriented a material of a data carrier having an optically changing secret protective element. CONSTITUTION: An optically changing secret protective element made of a liquid crystal material at the data carrier 20. The element has a plastic layer 21 made of a liquid crystal polymer exhibiting a glazing of a remarkable color at the room temperature such as, for example, a secret protective yarn 13a. Accordingly, it can be easily processed to a semi-fabricated product or a complete product according to plastic characteristics of the polymer, and the element of the entirely different type can be manufactured. Thus, a forgery using a color copier can be prevented.