To certainly perform positioning by positioning a short side by butting a rectangular plate on a short side protector by firstly moving only a corner pressing material forward by a certain distance in starting a clamp operation of a pressing material progressing mechanism, and by positioning a long side by butting the rectangular plate on a long side protector by simultaneously moving the corner pressing material and a long side pressing material forward subsequently after forward movement by the certain distance.

A placing block 13 comprises a block 26 for supporting the rectangular plate 25, the long side protector 27 for receiving a first long side 53 of the rectangular plate 25, the short side protector 31 for receiving a first short side 55, the corner pressing material 32 for pressing a first corner part 61 to a corner 65, the long side pressing material 33 for pressing a proximity of the short side protector 31 of a second long side 54 toward the long side protector 27, and the pressing material progressing mechanism 34 for moving the corner pressing material 32 forward by the certain distance Sf and then moving the long side pressing material 33 forward.