Automatic cutting device for printed supports comprising: - a feeding direction of a printed support; - a first sliding plane surface in the feeding direction of the printed support to be cut; - a second sliding plane surface in said feeding direction of said printed support after it has been cut, wherein said second sliding plane surface is placed at a distance from said first sliding plane surface along said feeding direction and defines together with the first sliding plane surface a transversal cutting area having a main dimension along a transverse axis, perpendicular to the feeding direction; - at least two cutting units configured to be able to move along the transverse axis within the transversal cutting area so as to intercept and cut the printed support; and - an electronic control unit configured to control the movement of the at least two cutting units; characterized in that it also comprises an array of fins arranged in a comb, cantilever supported at said second sliding plane surface, and elastically constrained in said array so that they can be elastically flexed along the transverse axis, in which said array: - is configured to move, controlled by the electronic control unit, from a closed configuration, in which all the fins protrude from said second sliding plane surface towards the first sliding plane surface and occupy the transversal cutting area, to an open configuration in which they leave free said transversal cutting area so as to allow undisturbed movement along the transverse axis of the at least two cutting units, - it is configured, when in closed configuration, to sustain the printed support and / or cut portions of the printed support when a free edge of the printed support passes from the first sliding plane surface to the second sliding plane surface. - a feeding direction of a printed support; - a first sliding plane surface in the feeding direction of the printed support to be cut; - a second sliding plane surface in said feeding direction of said printed support after it has been cut, wherein said second sliding plane surface is placed at a distance from said first sliding plane surface along said feeding direction and defines together with the first sliding plane surface a transversal cutting area having a main dimension along a transverse axis, perpendicular to the feeding direction; - at least two cutting units configured to be able to move along the transverse axis within the transversal cutting area so as to intercept and cut the printed support; and - an electronic control unit configured to control the movement of the at least two cutting units; - is configured to move, controlled by the electronic control unit, from a closed configuration, in which all the fins protrude from said second sliding plane surface towards the first sliding plane surface and occupy the transversal cutting area, to an open configuration in which they leave free said transversal cutting area so as to allow undisturbed movement along the transverse axis of the at least two cutting units, - it is configured, when in closed configuration, to sustain the printed support and / or cut portions of the printed support when a free edge of the printed support passes from the first sliding plane surface to the second sliding plane surface.