To fix two parallel square steel pipe battens disposed outside of a form plate to the form plate while using only a rod-shaped fastening tool with a wedge hole and a wedge plate without using any patch together.

A fastening tool 4 with a wedge hole is disposed between two parallel square steel pipe battens 9A and 9B. A wedge plate 10 comprises protrusions 15 and 16 in both ends of one side 11 in the length direction thereof. In the state where the one side 11 is directly abutted to outer side surfaces of the two parallel square steel pipe battens 9A and 9B without interposing any patch between the square steel pipe battens 9A and 9B, the wedge plate 10 is driven into a wedge hole 7 of the rod-shaped fastening tool 4 with a wedge hole orthogonally to a length direction of the two parallel square steel pipe battens 9A and 9B. In the state where the two parallel square steel pipe battens 9A and 9B are positioned between the protrusions 15 and 16 in both ends of the one side of the wedge plate 10, the two parallel square steel pipe battens 9A and 9B are pressed and fixed to the side of a form plate 1 by the wedge plate 10.