PURPOSE: To prevent the copy and the recopy of a secret document, etc. by preparing a form disabling the copy when it is set to a copying machine.

CONSTITUTION: A ground color surface which is developed in black when it is copied, and a continuous pattern making the contrast against this ground color surface distinctive, and constituting to dazzle a naked eye are formed. That is to say, the ground color surface 2, for instance, consisting of a net point of 150 lines.50% is printed by ink of a sepia tone on the whole surface of a form 1, also a continuous pattern 3 which has combined a vertical and horizontal lattice-shaped pattern of about 1mm interval with a tortoise shell-shaped pattern whose diameter is 4W5mm is printed at the same time, and a black ink character is written on this from by writing or printing. As for the form obtained in this way, the constrast of the ground color surface 2 and the continuous pattern 3 becomes remarkable, the ground color surface and the pattern look light and dark, respectively, and a density difference is observed in both of them. Accordingly, a character written on the form is seen clearly in a state as it is, but when it is copied, it is assimilated to the pattern 2 and cannot be discriminated. That is to say, when this form is copied, the pattern and the character cannot be discriminated from each other, and the character cannot be read.