PURPOSE: To provide a copy form set which prevents secret information from being leaked and can confirm its information easily and swiftly.

CONSTITUTION: In a copy form set 1 comprised of a plurality of sheets of form paper, it is comprised by providing a secret information entry part 4 on a face side of the upper part of the form paper 2, on the one hand, a pressure-sensitive transferred ink layer 5 which has the same color as the surface of the lower part form paper 3 facing on the upper part of the form paper 2 or transparence and a different pH value from that of the lower part of form paper 3 on a position corresponding to the entry part 4 of the rear side.