PURPOSE: To cut metal band into accurate widths with less warp and prolong lives of the round cutters used by performing the cutting in the condition that each metal band to be cut is tensed in its width direction.

CONSTITUTION: Metal bands 1 or the like fed continously are cut into minor widths by round cutters 3, 3' while each band 1 is tensed sidewise with tension provision means 5, 5'. Because of this tension applied, the resistance of the metal band 1 against shearing force will be small and the reactive force to the shafts 2, 2' on which the round cutters 3, 3' are fixed also be small, so that the shafts 2, 2' do not tend to deflect. Accordingly, the amount of overlapping of the edges of cutters 3, 3' at the central and end parts of shaft 2, 2' do not vary so much as well as the forces applied to the cutters 3, 3' during cutting or band lessen, so that lives of the cutters 3, 3' will be prolonged and a precision cutting with less warp obtained.