To secure a precise locking state by forming oblique directional slits toward the tip from the intermediate part both side edges in a claw piece, bending the claw piece on a line connecting the inmost end of these slits, and overhanging/forming locking projection pieces with the edge side of the slit as an oblique line in the inverse direction of the overhang direction.

When installing an ornament member in a part of the surface of a door trim having a trim base material 11 covered with a skin material 14 through a pad layer 13, oblique directional slits 4, 4 proceeding to the tip from the intermediate part both side edges of a claw piece 3 are formed, this claw piece 3 is pushed in a slit hole 12 until the forward bending part 3a of the claw piece 3 projects from the reverse of the trim base material 11, and the bending part 3a is bent at an almost right angle from a line connecting the inmost end of the slits 4, 4. Locking projection pieces 5, 5 with the edge side of the slits 4, 4 as an oblique line overhang in the opposite direction of the overhang direction of the bending part 3a from the bending part to be locked on the hole edge of the slit hole 12 along the reverse of the trim base material 11 by using resiliency of a skin thickness.