PURPOSE: To improve operating efficiency by simplifying joint operation while enhancing the reliability of the strength of a joint section.

CONSTITUTION: In the joint structure of a precast concrete board, a long-nut insert 3 with an anchor is buried into the side face 2A of the precast concrete board 2 while a connecting hole 5 is bored at a place corresponding to the exposed end face of the insert 3 in a handrail board 4. A connecting bolt 10 is inserted into the connecting hole 5, and coupled with the insert 3. When the precast concrete board 2 is joined with the handrail board 4, the connecting bolt 10 is inserted from the connecting hole 5, and combined with the insert 3, and the inside of the connecting hole 5 is filled with mortar M2 and mortar M2 is hardened, thus joining the precast concrete board 2 with the handrail board 4.