Attachment device for attaching to a floor-cleaning machine, having a base frame, which has a front end and a coupling end, wherein, in the state in which the attachment device is attached to the floor-cleaning machine, the coupling end is oriented in the direction of the floor-cleaning machine and the front end is oriented away from the floor-cleaning machine, having a supporting element, which is designed so that, when the attachment device is in a disassembled state, in which it has been released from the floor-cleaning machine, said supporting element supports the attachment device, by way of a free end, on a ground surface, having a first coupling element, which is attached to the base frame and is configured such that, when the attachment device moves vertically in the direction of the ground surface relative to the floor-cleaning machine, said first coupling element can engage with a second coupling element on the floor-cleaning machine such that it is locked against any further vertical movement and movement parallel to the ground surface relative to the floor-cleaning machine, having a pressure-exerting element, which is attached to the base frame in a pivotable manner and can come into abutment, by way of a free end, with a preferably vertically running abutment surface on the floor-cleaning machine, having an actuating element, which can be pivoted about a horizontally running axis relative to the base frame, and having an actuating shaft, which is retained on the base frame such that it can be pivoted about a pivot axis and which is coupled to the actuating element, wherein the first coupling element and the pivot axis define a transverse plane, in which the pivot axis runs and which runs upwards from the ground surface, through the first coupling element, in a direction transverse to the direction of travel of the floor-cleaning machine, wherein the supporting element is coupled to the actuating shaft and, when the actuating shaft pivots, is pivoted between an extended position and at least one retracted position, wherein the free end of the supporting element in the extended position is at a greater distance from the base frame than in the at least one retracted position, wherein the pressure-exerting element is coupled to the actuating shaft and, when the actuating shaft pivots, is pivoted between a release position, a coupling position and a disengagement position, wherein the placement of the free end of the pressure-exerting element in the release position is closer to the front end, as seen along an adjustment direction which runs perpendicularly to the transverse plane, than that in the disengagement position, and wherein the placement of the free end in the coupling position is located, as seen along the adjustment direction, between that in the release position and that in the disengagement position, and wherein the pressure-exerting element and the supporting element are coupled to the actuating shaft such that, in the release position, the supporting element has been pivoted into the extended position, and that, in the disengagement position and the coupling position, the supporting element is in one of the at least one retracted positions.