To prevent the break of a blade edge and also obtain a throwaway tip with a small cutting resistance.

The blade edge of a platy throwaway tip is formed so as to cut by both sides (rake surface sides) of the plate thickness direction. A land part 4 for constituting the blade edge 2 is formed in nearly square ring shape on both rake surfaces of the plate thickness direction of the throwaway tip and a tip breaker which is a mold breaker is provided in nearly square ring shape across an entire periphery on the inside of the land part 4 and a seat 7 is provided on the inside of the tip breaker. The land part 4 is composed of the chamfering part 8 of the tip side of the blade edge 2 and the straight part 9 of a center side and especially, set so that the surface of the plate thickness direction of the straight part 9 and the surface of the plate thickness direction of the seat 7 are formed to the same plane.