The purpose of the present invention is to provide a device for brush-polishing by means of a polishing brush that rotates and revolves as in a planetary motion, wherein the conditions to polish can be easily set in accordance with the properties of the workpiece and the purposes to polish. A brush unit has a polishing brush that rotates and revolves. The brush unit includes a mechanism for driving the rotation that rotates the polishing brush and the mechanism for driving the revolution that revolves it. By adjusting the speed of the rotation by the mechanism for driving the rotation the capabilities to polish the workpiece are enhanced. By adjusting the speed of the revolution by the mechanism for driving the revolution the entire workpiece is uniformly polished.