To provide an index sheet in which an index piece protruding from the end edges of notebooks is partially positioned for easy display effects in a state being attached to the cover of the notebooks.

The index sheets 11 to 15 are respectively attached to the outside or inside the cover 20 constituting a plurality of notebooks 10. The index sheets include a planar sheet body 21 corresponding to the planer shape of each cover 20, a first and second extension sheets 23, 24 to be folded inward continuously at both lateral ends of the sheet body 21, and the index piece 28 partially protruding from the upper end of the first extension sheet 23. Each index piece 28 is provided at a position where the index piece is shifted laterally for each notebook 10.