To surely fixing a door inner seal and enhance variations of skin specification in a method and an apparatus for fixing the door inner seal.

On the rear surface of a waist flange 23 in a door trim body, when an inclined lightening 25 whose depth becomes greater as it becomes further away from an attachment hole 24 is formed at an overlapping portion of a bent piece 33b of a locking claw 33, and the locking claw 33 is bent by a machine roller 64 in the fixing apparatus, the bent piece 33b of the locking claw 33 is bent into an acute angle so that the locking claw 33 is pressed against the inclined lightening 25 by slidingly operating the machine roller 64 so as to be inclined a predetermined angle with respect to an attachment surface of the waist flange 23. Even when buckling phenomenon of the locking claw 33 occurs after the attachment is completed, the locking claw 33 has a bent angle of at least 90°, thereby ensuring an appropriate bending attitude of the locking claw 33.