PURPOSE: To prevent the vigorous collision of parts against each other in a barrel, to prevent the flawing of these parts and to make it possible to make plating thicknesses uniform and to uniformly and smoothly polish the parts by rotating the respective parts.

CONSTITUTION: The barrel 2 is formed to a cylindrical shape and it is bored with plural holes 23 on its outer periphery. A side face 21 is formed in one side part of the barrel 2. The side face is integrally provided with a gear 22 to which the rotating power from a driving device 1 is transmitted. The other side of the barrel 2 is freely attachably and detachably provided with a cap 5. The barrel 2 is internally provided with a partition 3 and holds the plural parts 6 contactably and freely rotatably with the inner peripheral surface of the barrel. Both side parts of the partition 3 are provided with projecting parts 31. These projecting parts penetrate respectively the central part of the side face of the barrel 2 and the central part of the cap 5 and are fixed at their front ends to a frame 4. The partition 3 has an energizing property and is conducted to one terminal 71 of an external power source via the projecting parts 31.