A printing plate cylinder for a printing machine has a rotatable cylinder mandrel and a sleeve that is at least partially positionable over the cylinder mandrel. The angular positions of the mandrel and the sleeve are alignable to each other by a male register element which is fixed on one of the two elements to be aligned, and a female register element which is part of the corresponding other element to be aligned. Both the male and female register elements remain in working connection with each other if the elements to be aligned are in the set position relative to each other. At least one of the male and female register elements is controlled by movement of the other element to be aligned.