PURPOSE: To maintain the quality of external appearance of the interior of a vehicle with no local deformation, at a satisfactory level, by providing a stey which may absorb force causing thermal distortions in a resin part.

CONSTITUTION: A stey 11 in a plate-like form is prolonged and projected from the main part 17 of a resin part 1, having a cross-section shape such that its plate thickness is gradually increased from the lower end edge to the upper end edge of the stey 11, and further, an elongated flexible section 19 is formed in the intermediate section. The flexible section 19 is formed with vertical thin-plate sections 11a, 11b, 11c in three positions, and the center thin-plate sections 11b is folded outward while the front and rear thin-plate sections 11b, 11b are folded inward, thereby the stey has a hinge structur which allow the stey to move in the longitudinal direction of the vehicle body.