BINDER ASSEMBLY

PROBLEM TO BE SOLVED: To reduce labor to fix a sheet holding device to a cover by a method wherein an opening is provided on the inside of the plate being fixed to the cover, and one part of a pin which is reciprocatably attached to the sheet holding device, is selectively located in the opening, and the sheet holding device is fixed to the cover. SOLUTION: A pair of plates 28 which are arranged apart, are fixed to the back plate 14 of a cover, and at approx. the center of the plate, an annular protuberance 36 which has an opening inside and swells upward is located. From the lower surface of the plate 28, a plurality of deformable claws are hung. When the plate 28 is built up into the back plate 14 of the cover 12, the plate 28 is pressed to the back plate 14 in such a manner that the deformable claws may bite into the material forming the back plate. The deformable claws slightly expand to the outside, and fixedly attach the plate 28 to the back plate 14. A sheet holding device can be repeatedly attached to or removed from the cover, and can be easily built up or disassembled.