A cutting apparatus adapted for use in a machine tool. The cutting apparatus includes a mounting frame. A cutting unit is mounted rotatably in the mounting frame. A locking unit is connected to the mounting frame and the cutting unit, for restraining or permitting relative movement between the mounting frame and the cutting unit. A driving unit drives rotation of the cutting unit. A control unit controls the driving unit to drive rotation of the rotating shaft upon detecting that the relative movement between the mounting frame and the cutting unit is permitted. The control unit shuts off the driving unit upon detecting that the relative movement between the mounting frame and the cutting unit is restrained.