To prevent the damage of a building due to an earthquake, etc., by installing a pair or more of support bars, which are mounted rotatably on internal and external wall surfaces near to a joint section of one of the external walls of left-right buildings and in which free end sections are abutted against internal and external wall surfaces near to the joint section of the other.

Support bars 6 are set up at the corresponding sites of internal and external wall surfaces 5a, 5b near to a joint section 2 of one external wall 5 by fixing screws, and both end sections of urging springs 7 are fitted to the urging spring metal fittings of a pair of the support bars 6 respectively. An external cover plate 9 covering the support bar 6 placed on the outside is installed to the support bar 6, and an internal cover plate 12 covering the support bar 6 placed on the inside is mounted on the support bar 6. Even when left and right buildings are quaked in the front-rear and left-right directions by an earthquake, etc., the free end sections of the support bars 6 are moved in the front-rear and left-right directions, quaking is absorbed, the buildings are returned to an original state by the urging force of the springs 7 when quaking is stopped, and the damage of the buildings can be prevented.