To reduce the vibration generated on the basis of a cylinder groove impact at a time of a printing process and to dispensing with the force tightening a rubber blanket.

A rubber blanket unit 31 is composed of the rubber blanket 32 fixed to a support plate 2 and the leg parts 8, 9 formed by bending the edges of the support plate 2 are arranged so as to go over the end parts 38, 29 of the rubber blanket 32 to protrude and a plurality of press projections 18 individually supported by springs together pressing both bent leg parts 8, 9 of the support plate 2 to the side surfaces 14 of the slit 7 of a rubber cylinder 1 are provided. The press projections 18 are arranged side by side in an axial direction so as to act on both leg parts 8, 9 only in an almost right-angled direction and spring force and a spring process are set so that the mutual contact leg parts 8, 9 of the support plate 12 can be certainly clamped between the side surfaces 14 of the slit 7 and the press projections 18.