To rock a panel slightly, and to prevent the shear failure of the panel by inserting a support member with a projection between a fastener and the panel and between the vertical section of a backing plate and the panel.

A backing plate 4 is fixed to a ruler angle 3, and upper-stage ALC panels 1, 1 are carried on the horizontal section 4a of the backing plate 4. A tabular fastener 6 is screwed into anchors 5, 5 inserted from a header surface near to the fastener 6 under the state, and the lower end section of the upper-stage ALC panel 1 is installed. On the other hand, the vertical section 4b of the backing plate 4 is screwed into the anchor 5, and the upper end section of a lower-stage ALC panel 1 is mounted. In the structure, support members 8, 8, in which projections 8a are formed at the through-hole sections of bolts 7, are inserted between the fastener 6 and the ALC panel 1 and between the vertical section 4b of the backing plate 4 and the ALC panel 1. Accordingly, the ALC panels 1 can be rocked slightly while using the projections 8a as supporting points.