PURPOSE: To fix a container charged with the metal to be polished and a polishing small piece surely and easily in its detachment, by piercing plural insertion holes inside a discoid frame consisting of a nonmagnetic raw material, and making a container freely detachably from the insertion hole.

CONSTITUTION: A polishing small piece consisting of a lot of magnetic raw materials is charged into a container 10 together with the metal to be polished and linked by S, N poles mutually with its magnetization, when it is placed in the magnetic field where S and N poles approach at a fast speed alternately, but it is reversed because of the magnetic field being converted instantaneously, the linkage is released or the polishing small piece itself is abruptly rotated to become in a disturbed state, the polishing small piece is energetically intruded to the detail of the metal to be polished and the whole body is uniformly polished. In this case, the container 10 can be fixed without rotating it in an abruptly converting magnetic field by fixing a frame 11 having the insertion hole 15 of the container 10 at the specific position and inserting it into this insertion hole 15.