PURPOSE: To eliminate damage to an insulating layer and an inner layer pattern under a pattern cut part by varying irradiating magnification of a laser light in response-to an absorption factor of a different laser light according to a type of a metal pattern.

CONSTITUTION: A multilayer metal pattern 3 made of a chromium layer, a copper layer, a nickel layer and a chromium layer is irradiated with a laser light for cutting a pattern from a polyimide layer 2 formed on the layer 2 of an insulator formed on a surface of a board 1. In this case, in order to remove the chromium layer of surface metal 3a of the pattern 3, a laser light 4a having a low magnification is used. Then, after the metal 3a is removed, in order to remove a copper layer of an intermediate metal 3b and a nickel layer of an intermediate metal 3c, it is irradiated with a laser beam 4b having high magnification. Thus, if an object to be cut at its pattern has multilayers, a plurality of stage-cutting conditions are controlled to realize stable cutting.