PURPOSE: To obviate the deburring work by placing a tooth-shaped forging bevel gear with a surface where tooth shape is formed facing a trim die side, and machining a surface where tooth shape is not formed after putting into the trim die with a trim punch to cut excess thickness.

CONSTITUTION: A tooth-shaped forging bevel gear 10 is placed on a trim die 11 with a surface 10c which has a tooth shape 10b facing the trim die side, a trim punch 12 is lowered in an arrowed direction c, and a pressing surface 12a provided at the lower part of the trim punch 12 is aligned on the surface 10f side of a work 10. Besides, when the trim punch 12 is lowered, shearing force acts on excess thickness 10a of the work 10, the excess thickness 10a is cut, gradually so that external dimension on a surface 10e side where the tooth shape 10b is formed may become d as desired, and when the excess thickness 10a is cut completely, burrs 10g are generated. The work 10 is taken out from a hollow part 11b of the trim die 11, and the work 10 where trimming is completed by means of machining is made into a desired shape. The burrs 10g are automatically removed at the same time the machining is carried out.