PURPOSE: To maintain the proper function of a welded section for jointing a floor panel to a bracket.

CONSTITUTION: The front side of the bottom plate section 14 of a bracket 11 is formed to be a corrugated bead 30 bent in such a state as corrugated in the lengthwise direction of the section 14 and capable of elongation under the preset tension. A vertically extended slot 31 is formed on the lower side of a joint for the slope side 17 and horizontal side 16 of a bracket side plate 15. As a result, the bead 30 elongates to follow the deformation of a floor panel due to a rise, under the elongation of the plate 15 to expand the slot 31, in such a case where the floor panel rises along the same direction as a force acting thereon from a front slantwise upper position. Consequently, the side plate 15 and the bead 30 absorb the force, thereby preventing the floor panel from being separated from the bracket 11.