To provide the cutting device in which a generally used cutting tool not imparting supersonic vibration can be attached to a rotating spindle for supersonic vibration cutting.

The tool attaching portion 422 of a rotating spindle 42 is constituted so that a mounter 10 capable of mounting a cutting blade 152, which is a cutting tool different from a supersonic vibration cutting tool, can be attached detachably, wherein the mounter 10 includes a boss 110, and a flange 120 formed to project from the boss in the radial direction in order to support the cutting tool, and the boss is attached detachably to the tool attaching portion by means of a fastening bolt 130.