To reduce the difference between an actual temperature of a printing matrix of a printing plate and an appropriate temperature.

This printer 1 is configured of a plate cylinder 25a and a plate cylinder 25b, on both of which a printing plate is mounted, and a plurality of printing units 11 to 14 which are each made up including the plate cylinder 25a and the plate cylinder 25b, and operate to print a web. In addition, the printer 1 includes a temperature adjusting device 50 which adjusts the temperature of the printing matrix of each of the printing plates to be mounted on each of the plate cylinders individually by the unit of a group, when the printing plates to be mounted on the plate cylinders, are divided into the groups.