THROWAWAY TYPE CUTTING TOOL

PROBLEM TO BE SOLVED: To provide high clamping rigidity in spite of a great alteration in an outside diameter of a cutting edge by forming a pressing face in a wedge member and a pressed face in a throw-away tip diagonally to the direction in which these wall faces are extended. SOLUTION: When a supporter 13 is advanced toward a tool outer circumference side, a wedge member 17 is also advanced parallelly to the advancing and retreating direction of the supporter 13 along a wall face 12B toward a tool outer circumference side, so that the relative positional relationship between the wedge member 17 and the throw-away tip 15 is not changed. Therefore, a pressing face 17A in the wedge member 17 is always brought into contact with a pressed face in the throw-away tip 15 with a constant pressing area without respect to the advancing and retreating position of the supporter 13 when the diameter of rotation of a cutting edge 15A is varied, and sufficient pressing force and be secured. As a result, the throw-away tip 15 can be surely held, and high clamping rigidity can be provided.