Abstract: The present invention provides an index apparatus comprising a base, a cover, locking and unlocking means, indexing means, a coil spring, cards etc. When compared with conventional ones, the apparatus of the present invention has the following main features. The construction and the fitting to impart the opening capacity to the cover of an index apparatus are very simple. To mention more fully, the opening capacity can easily be given to the cover only by inserting the coil spring in the contracted state into the projections on the base without conventional fastening with iron core inserted into the coil spring. Unlike conventional ones, the index means of the index apparatus in the present invention is simple in its construction and easy to fit. The indexing means consists of two parts, the indexing member made of semi-hard synthetic resin and the slider made of elastic material, and is characterized by its easy fitting without any processing.