Vibration-proof structure for rotating body

A vibration-proof structure for a rotating body, comprising:

• a cylindrical rotating body having a rotation axis and including:
• an opening in an end along the rotation axis;
• and
• a hollow continuous with the opening and extending along the rotation axis;
• a weight in the hollow;
• a plurality of elastic members each disposed on an outer surface of the weight and holding the weight;
• a head member connected to the rotating body in such a manner as to close the opening and have an axis that coincides with the rotation axis;
• and
• a shank opposite to the head member across the rotating body and configured to be held by a spindle of a machine tool,
• the opening and the hollow each having a cross section in a shape of a circle with the rotation axis as a center,
• the weight having a columnar shape and an axis that coincides with the rotation axis,
• the head member having a depression in a portion to which the rotating body is connected and including a portion opposite to the rotating body to which portion a cutting tool is attachable,
• the weight including a protrusion protruding toward the head member and in the depression from a boundary between respective outer surface portions of the rotating body and the head member.