A throw-away tip of which two principal surfaces each comprises a land
surface 5 provided along the periphery thereof, a central surface 7
provided on the inside of the land surface 5, a recess (a chip breaker
groove) interposed therebetween, and at least one protrusion 8 that
extends from the central surface 7 toward the land surface 5, wherein
height of the land surface is made equal to the height of at least the
top surface of the protrusion 8 so that at least the top surface of the
protrusion of the central surface and the land surface both serve as
contact surface.