PURPOSE: To continuously polish a metal wire by feeding polishing powder while pressurizing it in spite of a simple structure.

CONSTITUTION: A metal wire 1 is inserted into the metal wire inlet and outlet 4, 5 of a container 3, then polishing powder 2 is filled into the container 3 from an upper opening 10. When rotors 6 are rotated while the metal wire 1 is traveled in the horizontal direction, vanes 7 provided on the rotors 6 stir the polishing powder 2 while applying the pressing force in the tangential direction of the locus. The polishing powder 2 and the metal wire 1 are pressed from many directions, and the whole surface of the metal wire 1 is polished. Since the polishing powder 2 is discharged together with the metal wire 1 guided out of the outlet 5, the total quantity of the polishing powder 2 in the container 3 is decreased, and the polishing powder 2 near the rotors 6 is partially decreased by the rotation of the rotors 6, however, the decrement is fed from the upper opening 10 of the container 3 by a polishing powder feeding device 9.