There are disclosed a method and device for polishing a metal ring, which is capable of polishing a side edge of the metal ring without performing barrel polishing or polishing by grinding stones. Subsequently to a projecting step of projecting a metal ring W by clearing means 6, a first brush polishing step of polishing one edge of the metal ring W by a polishing brush 60 is performed. Subsequently, an inverting step of inverting the metal ring W whose one edge is polished by the first brush polishing step is inverted by the inverting means 10 is performed. Subsequently, a second brush polishing step of polishing the other edge of the metal ring W which is inverted by the inverting step by the polishing brush 60 is performed. Moreover, a clearing step of clearing the metal ring whose other edge is polished by the second brush polishing step by clearing means 7 is performed.