PURPOSE: To prevent scratch from producing on a strip by making shearing blades installed on two knife drums opposed vertically not to contact with the strip.

CONSTITUTION: Eccentric gears 13, 14 and 15, 16 are installed in upper and lower knife drums 1 and 2, respectively, the gears are rotated by eccentric gear driving pinions 17, 18 and 19, 20 installed on eccentric gear driving motors M1, M2 and M3, M4, respectively, to revolve the both knife drums 1 and 2 about the eccentric gears 13, 14 and 15, 16, respectively, and to near and depart them to and from a strip 5, respectively. Pinch rolls 25, 26 and 27, 28 are provided at the inlet and outlet of the knife drums 1 and 2, respectively. When the strip is not cut, a shearing blade is not made in contact with the strip nor any scratch is produced since the both knife drums are separated from the strip. Also fluctuation of the strip under cutting is suppressed by the pinch rolls to maintain securer cutting.