PURPOSE: To manufacture a device of specified shape and size and assemble the, same easily and firmly by installing engaging structural bodies on respective panel support frames and fastening the same into the truss shape in the laminating direction by wires and fastening in the opposite direction by rod-shaped bolts when piles are assembled and accumulated to form a form for a concrete pillar of polygon shape.

CONSTITUTION: An adjacent panel 1 is positioned on a panel support frame 2 and made ready to be accumulated. An engaging structural body is formed on respective corners, and the same is composed of an eyenut 8, a frame fixing rod 12 screwed into the eyenut and running through a frame 2 and a rod retaining member 16, and the fixing rod 12 is fixed on the frame 2 through the retaining member 16 by a nut 18. Opposite engaging structural bodies are fastened by a rod-shaped belt 22, and wire ropes 24A and 24B are inserted through the eyenut 8 in the zigzag shape in the panel accumulating direction, and the whole is fastened into the truss shape. A fitting panel 8c is formed on the eyenut 8, by which spacers 25 and 26 for pressing the panel 1 are retained pivotably and movably back and forth.