PURPOSE: To work a filmlike body, such as hologram pattern, provided on the surface of an annular disk, which is easily peelable without peeling or damaging the filmlike body in the method for forming the outside diameter or inside diameter of the above-mentioned filmlike body.

CONSTITUTION: The disk HD is mounted to a chuck in the state of covering the part where the filmlike body HP is not worked with an annular protective jig 12. The disk is then rotated and the edge of a bit BT is moved in the direction perpendicular to the surface of the filmlike body HP, by which the bit is cut deep into the filmlike body HP down to its thickness or above; thereafter, the bit BT is moved in the relief direction of the diametral direction.