To produce coated paper as top paper or upper paper for pressure sensitive copy paper set which adheres each other in the set but not adheres between the sets: the top paper does not adhere to lower paper in the pressure sensitive copy paper set comprising pressure sensitive copy paper sheets stacked in a predetermined order by subjecting at least an edge of either one of the back of the top paper or the surface of the upper paper to a treatment with an aqueous coating solution, in sizing as the set comprising the top paper such as wood free paper which is uncoated paper, or the like, stacked on the upper paper.

The ultrasonic transmission curve caused by penetration of water at least from a part where is the edge of one face of the uncoated paper or the upper paper for the pressure sensitive copy paper and is coated with the aqueous coating solution followed by drying is characterized by possessing at least two critical points on the lowering slope line after reaching the maximum value.