Patent ID: 8708620

Claim:
A tool holder comprising: a shank member to be held by a tool spindle of a machine tool; a cylindrical body coupled to the shank member; an attachment hole formed in a radially inner portion of the body; an anti-vibration device fitted to a radially outer portion of the body; and a bolt, wherein a straight shank of a cutting tool is inserted into the attachment hole, the bolt is inserted in a radial direction through the anti-vibration device to fix the straight shank of the cutting tool to the attachment hole of the body, wherein the anti-vibration device includes: a ring-shaped first anti-vibration member fitted to the radially outer portion of the body of the anti-vibration holder; a cylindrical second anti-vibration member fitted to the radially outer portion of the first anti-vibration member; and four O-rings arranged at radially inner and outer portions at both ends of the first anti-vibration member, wherein each end of the first anti-vibration member has a trapezoidal cross-sectional shape, the O-rings are each arranged on one of the inner and outer circumferential surfaces of the ends of the first anti-vibration member, and the first anti-vibration member is in contact with two of the O-rings in a wedge-like manner.