Abstract: A fastener for binding documents having binding holes includes a fastening band and a back cover having binding holes. A layer of adhesive on one surface of the back cover is covered with a peel-off paper. The fastening band is inserted through the binding holes of the documents and the back cover. According to one embodiment, the fastening band includes a flat board part that holds the documents down and first and second clasp parts having engagement crenelations connected to both ends of the flat board part. The documents are securely bound by bending the first and second clasp parts to lock the engagement crenelations. Then, the peel-off paper is removed and the back cover is folded to conform to the documents and glued to the documents. According to another embodiment, the fastening band includes a flat board part having a narrow clasp part. The flat board part includes multiple spaced clamp holes. The clasp part is inserted into one of the clamp holes to bind the documents.