To provide a binder for a notebook in which a wide variety of pigeonholing and sorting of notebooks is made possible and sheets can be filed in a plurality of divisions even when electronic recording media or the like are contained.

Three or more replicated parts 4a, 4b, 4c are provided in parallel and at an equal interval in a base sheet 1 and a filing fitment 5 is fixed to the inner face of each of the replicated parts 4a, 4b, 4c and further, the base sheet 1 is folded back inwardly at each of the replicated parts 4a, 4b, 4c. Thus the binder for the notebook is constituted by equalizing a planar area to an area between the adjacent two replicated parts 4a, 4b, 4c.