PURPOSE: To make efficiently a truly circular wire of an extra small diameter as well with die grooves by housing plural pairs of shaft-shaped revolving rollers having the plural die grooves into a roller box in such a manner that the rollers contact alternately with the wire to be worked from the top, bottom, right and left and rotating cooperatively all the rollers.

CONSTITUTION: The front end of the wire, when inserted through an insertion hole 9 provided to the roller box 1, is engaged with the grooves 2 of the revolving rollers 3 and is then engaged with the grooves 2 of the rollers 3 which are positioned successively thereafter and are alternately provided to the top, bottom, right and left. The wire is thus successively rolled from vertical and lateral directions. The shaft-shaped rollers 3 are extremely small in diameter as compared with the rolling force and therefore the roller pitch is short and all the rollers revolve. These rollers are freely rotatably fixed in the roller box in such a manner that the surfaces of all the rollers fixed to each other provide the datum plane. The turning of the wire in the grooves 2 is thereby averted and the deviation of the rolling down direction and the rolling angle of the wire is obviated.