A device for feeding self-adhesive or "pressure sensitive" labels to a labelling machine comprising: a frame; supporting means, associated with the frame, for a reel of web on which self-adhesive or "pressure sensitive" labels are applied; a detaching station for detaching the labels from the web, associated with the frame; means for recovering the web, which are associated with the frame; there being a web running path between the supporting means, the detaching station and the recovery means; web return means, associated with the frame and positioned along the running path; movement means for moving the web which are associated with the frame for moving the web along the running path, the movement means in turn comprising: a motor-driven roller associated with the frame, the motor-driven roller being able to rotate about a first axis of rotation and move the web by contact with it; at least one pressure unit for pressing the web against the motor-driven roller, the pressure unit comprising: at least one contact roller which can rotate about a second axis of rotation parallel with the first axis of rotation at least in the opposite direction to the motor-driven roller, the contact roller in practice being able to be pressed against the motor-driven roller for clamping the web between it and the motor-driven roller; and at least one support for the contact roller, the support being associated with the frame and movable relative to it between an operating position, in which the contact roller is pressed against the motor-driven roller, and an insertion position in which the contact roller is distanced from the motor-driven roller and allows insertion of the web between them; the movement means also comprising at least one switching element associated with the support for causing the support to switch at least between the operating position and the insertion position, the switching element and the support being able to adopt a first reciprocal configuration in which the switching element keeps the support in the operating position and a second reciprocal configuration in which the switching element keeps the support in the insertion position; and characterised in that the switching element and the support can also adopt a third reciprocal configuration in which the support is also movable at least between the insertion position and a maintenance position in which the contact roller is further from the motor-driven roller than when the support is in the insertion position. a frame; supporting means, associated with the frame, for a reel of web on which self-adhesive or "pressure sensitive" labels are applied; a detaching station for detaching the labels from the web, associated with the frame; means for recovering the web, which are associated with the frame; there being a web running path between the supporting means, the detaching station and the recovery means; web return means, associated with the frame and positioned along the running path; movement means for moving the web which are associated with the frame for moving the web along the running path, the movement means in turn comprising: a motor-driven roller associated with the frame, the motor-driven roller being able to rotate about a first axis of rotation and move the web by contact with it; at least one pressure unit for pressing the web against the motor-driven roller, the pressure unit comprising: a motor-driven roller associated with the frame, the motor-driven roller being able to rotate about a first axis of rotation and move the web by contact with it; at least one pressure unit for pressing the web against the motor-driven roller, the pressure unit comprising: at least one contact roller which can rotate about a second axis of rotation parallel with the first axis of rotation at least in the opposite direction to the motor-driven roller, the contact roller in practice being able to be pressed against the motor-driven roller for clamping the web between it and the motor-driven roller; and at least one support for the contact roller, the support being associated with the frame and movable relative to it between an operating position, in which the contact roller is pressed against the motor-driven roller, and an insertion position in which the contact roller is distanced from the motor-driven roller and allows insertion of the web between them; the movement means also comprising at least one switching element associated with the support for causing the support to switch at least between the operating position and the insertion position, the switching element and the support being able to adopt a first reciprocal configuration in which the switching element keeps the support in the operating position and a second reciprocal configuration in which the switching element keeps the support in the insertion position; and characterised in that the switching element and the support can also adopt a third reciprocal configuration in which the support is also movable at least between the insertion position and a maintenance position in which the contact roller is further from the motor-driven roller than when the support is in the insertion position.