BINDER

PROBLEM TO BE SOLVED: To provide a binder capable of preventing a spine from being distorted due to weight of documents, regarding a metallic binder.SOLUTION: The metallic binder 30 is fixed to the spine of a file body in which a front cover, the spine and a back cover are bendably and successively connected. The binder 30 includes: a base 51 fixed to the inner surface side of the spine; a pressing plate 52 provided integrally with the base 51 and positioned away from the base 51 keeping a prescribed interval; a pair of insertion grooves 53 respectively positioned on both sides of the base 51 and formed within a gap of the base 51 and the pressing plate 52; and a pair of side plates 60 arranged on both sides of the base 51 and capable of being inserted to the insertion grooves 53 respectively. Also, an insertion part 81 may be positioned away from the inner surface of the spine when a side plate 60 is abutted to the inner surface of the spine.