PURPOSE: To achieve cost reduction through a reduction in the number of part items and to enable staples to be installed easily by magnetically attracting an enclosed line of U-shaped staples into a guide by means of a magnetic substance, and eliminating the need for a spring or a presser to be placed inside the guide.

CONSTITUTION: A guide 2 in which staples are installed is placed at the center, a presser 3 into which the staplers are inserted is provided above the guide 2, a pedestal 4 for folding the ends of the staples is provided beneath the guide 2, and a magnetic substance 2d is provided at the end 2c of the guide 2. A vacant space 2e for passing the staples through a bottom 2a when they are pressed with the presser 3 while being attracted magnetically by the magnetic substance 2d is provided in front of the magnetic substance 2d. The guide 2, the presser 3 and the pedestal 4 are rotatably supported on a common shaft 5 which passes through their respective rear ends 2B, 3B, 4B. A non- photosensitive coating that does not react to the light rays of copiers is applied to the portions of the staples corresponding to their U-shaped bottoms.