Abstract: This invention relates to a polishing device which may polish the surface of a hard body such as metal, rock, glass or hard plastics into a perfect spherical shape. Each polishing device may also be applied for the mass-production of lenses, concave and convex. The polishing device comprises three identical polishing dishes mounted on the front ends of three rotating shafts which are positioned on three lines radiating from one point on a plane with an angular interval of 120.degree., respectively. Said polishing dish has a concave polishing surface and the three polishing dishes are adapted to support a body to be polished at the center of the device and to rotate in contact with the body. Therefore, it may be polished into a perfectly spherical shape.