A print medium quality adjustment system includes an inspection watermark medium output device 11 having an inspection watermark signal generation unit 101 that generates at least one inspection watermark signal, generates a watermark signal image by disposing the inspection watermark signal(s) in an arbitrary arrangement, and generates inspection training data 105 having digitally recorded therein the inspection watermark signal(s). An inspection medium output unit 103 prints the inspection watermark image onto a medium. A watermark quality inspection device 12 has an output unit 106 that scans the printed medium, a signal detection unit 107 that extracts embedded watermark information, and a print quality judgment unit 108 that judges the watermark quality by comparing the extracted watermark information with the inspection training data. Based upon the quality judgment results, a print adjustment value 110 is generated to be used to improve the print quality.