Provided is a technique capable of reducing an influence of a change in web conveying speed on misregistration. A multi-color printing system prints on a web with a plurality of plate cylinders. The multicolor printing system includes: a determining unit (55) for determining whether or not the conveying speed of the web is changing; a constrasting unit (57) for controlling a plurality of plate cylinders in accordance with the determination result by a determining unit (55), in order to avoid shifting of a printing pattern to be printed on the web by the plurality of plate cylinders.