To provide a registering regulator for a printing machine for facilitating a regulating operation with a simple structure.

The registering regulator for a printing machine comprises a pair of right and left axle-cases 7 for pivotally supporting both end axles 5 of a plate cylinder 1, and the axle-case moving mechanism 11 provided at each case 7 to move the case 7 along a guide member 10. In this case, the cases 7 are suitably moved to regulate relative positions of the cylinder 1 to a rubber cylinder, thereby correcting a deviation of registering in a top and bottom direction or oblique direction of a printing sheet.