To solve a problem that: an upper end side of a reinforcement brace is mounted to a hanging bolt by a mounting bolt and a mounting metal fitting in assembling work of the reinforcement brace for reinforcing a ceiling structure, and in this case, a clearance occurs between the tip of the mounting bolt and the hanging bolt because the angle between the mounting bolt and a fitting surface to reinforcement brace is adjusted.

A part corresponding to a conventional mounting bolt is configured by two members, that is, a tip abutting bolt 12 and a relay shaft bolt 13. Rotation control parts 35, 36, 45, 47 are provided in both the bolts 12, 13 so that the tip abutting bolt 12 co-rotates with the relay shaft bolt 13 when rotating the relay shaft bolt 13 in a screwing direction. Thus, the tip of the tip abutting bolt 12 can be abutted to a hanging bolt. Moreover, a retreat prevention device 14 is provided so as to prevent the tip abutting bolt from retreating when rotating the relay shaft bolt 13 in a screwing direction for adjusting the angle of a fitting surface 50 of the relay shaft bolt 13.