PURPOSE: To enhance the efficiency in cutting a cast etc. by radially arranging cutter elements each having a main and side cutting edges, and by conducting the cutting while the cutter element is strongly pressed to the periphery of a tubing with no core inserted.

CONSTITUTION: A drive shaft 19 is rotated to advance and retract a cutter holder 2 along a guide through an intermediate gear 15, pinion 14, crank shaft 7, crank pin 10, and crank arm 13, and cutting is conducted while cutter elements 1 are strongly pressed to the periphery of a metal tubing 3 with no core inserted. Each cutter element 1 is equipped with a main 4 and side cutting edges 5. This provides cutting at a high speed with simple construction.