Abstract: A binder has a device for opening and closing a binder for storing sheets with at least one mechanism arranged in the area of the back of the binder. The mechanism comprises at least two spaced-apart strips which are movably interconnected by at least one common hinge, which strips are adapted for connection to the binder and are movably connected to a link means in such manner that the opening and closing motion of the binder produces a simultaneous positively guided motion of the hinge means. The link means comprises a pivot means which is pivotally connected to a centre strip of the hinge means via a centre axis which is a first pivot centre and which extends substantially transversely to the longitudinal direction of the back of the binder.