PURPOSE: To prevent a peeling-off of the interface between a bracket and a resin layer or a deformation of the bracket by providing a connecting part to connect with the other member and a bending part to bend from the connecting part to the surface side of the formation good, to the bracket buried in a resin formation good.

CONSTITUTION: In a trimming process after forming a formation good 12, a water jet W spraying from the surface side to a bracket 3 strikes the bending parts 8 of the bracket 3. The water contacted to the bending parts 8 flows to the connecting parts 7 side of the bracket 3, and exhausted from the ends of the bending parts to the rear side of the formation good 12. As a result, the water is prevented from flowing in the parts of the bracket 3 buried in a resin layer 11, and a peeling-off of the resin layer from the bracket is prevented. Furthermore, since the water pressure is never applied vertically to the surface of the bracket 3, the bracket 3 is also prevented from a deformation.