PURPOSE: To prevent a supporting part of an intermediate panel provided between a panel supported by an upper beam and a panel supported by a lower beam from being damaged in the case of an earthquake.

CONSTITUTION: A connecting part between the upper end of an intermediate panel 6 and a panel 4 on the upper side is referred to as an upper connecting part 10, while a connecting part between the lower end of the panel 6 and a panel 5 on the lower side is referred to as a lower connecting part 11. Each of the part 10 and the part 11 has such a construction that allows horizontal displacement and displacement in a bending dirction between the adjacent panels which are connected with each other by the connecting part.