PURPOSE: To securely connect a cutter body to a cutter holder, by a method wherein a pin, which has two plane parts, crossing each other at right angles, at sides in an axial direction, and a lamellar elastic substance, made of solid rubber, are placed in a pin hole.

CONSTITUTION: A pin 3, which securely fix a cutter body 1 to a cutter holder 2, has two plane parts 3a and 3b at the sides, which are properly used through the insertion, drawing-off, and the rotation of the pin, and according to a state at a time when the cutter body is connected, and has two staged parts 3c and 3c' which binds the movement in the axial direction of the pin at a rotating time. The connection is performed such that the pin 3 is first inserted at a position where the plane part 3a of the pin 3 is positioned facing and opposite to an elastic substance 10 being inserted into a pin hole 4 beforehand. The pin 3 is then turned by 90°, and this causes other plane part 3b to pressurize and deform the elastic substance 10, and simultaneously, causes the staged part 3c to make cpntact with the projection part on the elastic substance to bind the pin 3.