There has been constructed a piezoelectric pressure sensitive element built into a printing plate. The sensing part of the element is small in comparison with the width of the zone of pressure in the nip. This renders it possible to study the pressure distribution in the nip as well as the maximum printing pressure. A description is given of the design of the pressure sensitive printing plate, and of the electrical system for recording the pressure curves. The device has been used together with a Vandercook no. 4 proof press to investigate the relationship between the printing pressure and the packing material and packing thickness of the impression cylinder, the uniformity of the pressure and its dependence on the formation of the paper to be printed.