PURPOSE: To heighten the capacity of barrel polishing, by coating the inside surface of a barrel with a material appropriate for the polishing and by forcedly vibrating the barrel to cause polishing flow motion.

CONSTITUTION: A material 2 such as carborundum and bauxite, which is appropriate for polishing, is conjoined to the inside surface of a barrel 1 by coating or the like. The barrel 1 is supported by springs 3. A vibrating motor 4 is installed in an appropriate position at the bottom of the barrel 1 to uniformly cause vibration and flow motion which meet the machining conditions of a workpiece. The workpiece is put into the barrel 1 through an inlet port 5. The workpiece is displaced in the barrel while being spirally revolved therein. The workpiece is thereafter taken out of an outlet port 6.