Abstract: A device for treating the surface of workpieces, in particular of vehicle bodies, includes a gantry in the form of a frame. The latter has a through opening into which a workpiece may be introduced. At least one guide rail is secured to the gantry and is guided around the workpiece in an arc or circle shape. At least one carriage may be moved preferably by motor along the guide rail and carries a holding arm for the tool. This holding arm is constructed such that the tool is movable in the direction of the workpiece and may be brought into various angular positions in relation to the surface of the workpiece. In addition, a device is provided by means of which a relative movement may be performed between the workpiece and the tool in the axial direction of the through opening. This device is very versatile and makes possible a rapid movement of the tool at high speed and with high dynamics and a high level of precision.