A joint cover includes rails attached to the right and left building portions adjacent sides of the joint parts between the right and left building members. At least two or more support members are disposed across a joint gap at a sloping state, both ends thereof being supported movably by the rails attached to the side walls pairs. A plurality of support bars for retaining joint plates is provided pivotably at a fixed interval on the support members. The plurality of joint plates is attached to the support bars respectively, each joint plate being overlapping at a fixed width and being maintaining a overlapping state when the width of the joint gap between the two building members expands or contracts, so that the transportation and assembly operation can be done efficiently, and the joint cover can move smoothly following swing and oscillation movement due to earthquake, or the like.