A tool holder holds a cutting tool that cuts a workpiece while revolving about a rotational axis. The tool holder has a fixed part and a cutting part. The fixed part is held by a main shaft of a machine tool. The cutting part is provided integrally with the fixed part and has an asymmetric shape with respect to the rotational axis. The cutting tool is attached to the cutting part. The cutting part has a one-side part and an other-side part. The one-side part has a largest protruding amount from the rotational axis in the cutting part when viewed from an axial direction. The other-side part is located on a side of the rotational axis opposite to the one-side part. A bulk density of the one-side part is smaller than a bulk density of the other-side part.