A shaft member having an engaging part at a lower part is formed to project from a front edge part of a plate-like fitting main body having a required thickness, and an engaging member having an engaging part at a lower part is mounted to a tip surface of the shaft member, the engaging parts communicating with each other, wherein the fitting main body has a gripping part formed of a through-hole at a central part and pin insertion parts which are formed collinearly in the vicinity of an upper edge part and a lower edge part at a rear side of the fitting main body, and wherein a shaft-member insertion part resisting shear stress is provided at a portion different from the pin insertion parts formed on the upper edge part and the lower edge part.