To compensate for a change in the width of a web to be printed attributed to fan out by adapting to different operating conditions by a simple and inexpensive way.

A rotator for compensating the fan out in a printing machine forms a base part and a head part protruding above the base part by a difference of a radial height in such a way that they are formed by a twist preventing connection along the rotating shaft or alternately adjoined each other by one part. The difference of the height in the radial direction is increased circumferentially from the minimum value existing along the first straight line shifted in parallel to the rotating shaft, to the maximum value existing along the second straight line shifted in parallel to the rotating shaft.