To provide an inexpensive inspecting device of the printed matter in regard to the inspecting device of printed matter for inspecting the quality of the printed matter under printing on line.

This inspecting device of the printed matter comprises a CIP3 data convertor including a PPF processing function for forming image data in a PPF format, in which image data are converted to a lower resolution, an image data processing device for converting multivalued image data constituting printed matter through a RIP processing into binary image data for recording an image in order to form a printing plate employed in printing equipment, an image reading means and a comparing means for inspecting the printed matter by comparing inspecting image data read with the image reading means with the image data in the PPF format obtained by the CIP3 data convertor.