A device for feeding self-adhesive or "pressure sensitive" labels to a labelling machine comprising: a frame; supporting means, mounted on the frame, for supporting a reel of web on which self-adhesive or "pressure sensitive" labels are removably attached, the supporting means in turn comprising a supporting plate on top of which there is a substantially flat sustaining surface on which in use the reel can be placed, the supporting means also comprising at least one guide element (28, 29) for the reel, the guide element (28, 29) defining an axis of rotation for the reel perpendicular to the sustaining surface and being designed in use to be inserted at least in a part of a central hole of the reel for in use guiding reel rotation about the axis of rotation; a detaching station for detaching the labels from the web, associated with the frame; feeding means for feeding the web to the detaching station, associated with the frame; and recovery means for recovering the web without labels from the detaching station, associated with the frame; wherein the supporting plate is removably associated with the frame, and wherein the supporting means also comprise a containment head switchable between an open configuration, in which in use it allows coupling with and uncoupling from the frame of the supporting plate with the reel placed at the sustaining surface, and an operating configuration, in which it allows the reel to be held between itself and the supporting plate, in any case allowing reel rotation guided by the guide element (28, 29), characterised in that the supporting means comprise prevention means for preventing rotation of the supporting plate, the reel in use being able to rotate about the axis of rotation by sliding on the sustaining surface. a frame; supporting means, mounted on the frame, for supporting a reel of web on which self-adhesive or "pressure sensitive" labels are removably attached, the supporting means in turn comprising a supporting plate on top of which there is a substantially flat sustaining surface on which in use the reel can be placed, the supporting means also comprising at least one guide element (28, 29) for the reel, the guide element (28, 29) defining an axis of rotation for the reel perpendicular to the sustaining surface and being designed in use to be inserted at least in a part of a central hole of the reel for in use guiding reel rotation about the axis of rotation; a detaching station for detaching the labels from the web, associated with the frame; feeding means for feeding the web to the detaching station, associated with the frame; and recovery means for recovering the web without labels from the detaching station, associated with the frame; wherein the supporting plate is removably associated with the frame, and wherein the supporting means also comprise a containment head switchable between an open configuration, in which in use it allows coupling with and uncoupling from the frame of the supporting plate with the reel placed at the sustaining surface, and an operating configuration, in which it allows the reel to be held between itself and the supporting plate, in any case allowing reel rotation guided by the guide element (28, 29),