To provide a method for removing paper dust of a rolled web in an offset rotary printing machine, by which printed matters of excellent printing quality can be obtained by sucking and removing paper dust remaining in cutting into small windings of the rolled web.

In this method for removing paper dust of the rolled web in the offset rotary printing machine, an air jet roll for jetting compressed air on both a front and rear web surfaces of the traveling rolled web is provided at an arbitrary position in front of a tension adjusting device in a paper feeding part of the rolled web, for scattering the paper dust stuck on the web surfaces to be sucked by a dust sucking member provided near the air jet roll, when printing either on one surface or on both surfaces by the offset rotary printing machine. The air jet roll for jetting the compressed air is hollow and is provided with circular jetting ports jetting the compressed air at a constant interval on the width direction of the roll surface.