To enable the back index of a loose-leaf file to be constituted without increasing the number of parts.

This loose-leaf file consists of a first slender base plate 3 for standing a plurality of file rings 1, a second slender base plate 7 for standing a plurality of file rings 5 butting against the file rings 1 of the first slender base plate 3, a pivotally attaching mechanism which is provided in one end of both base plates 3, 7 to pivotally attach both base plates 3, 7 mutually and a lock mechanism that is provided on other end of both base plates 3, 7 to mutually lock both base plates. In this case, the first base plate 3 and the second base plate 7 have the rear part 17 respectively exposed to the back. The rear part of the first base plate 3 has a slit 19 capable of inserting a back index plate through an opening provided along an edge part in the lengthwise direction on one side. The rear part 17 of the second base plate 7 has a press rib 21 in the position for closing the opening of the slit 19 at least partially when both base plates 3, 7 are closed, so that the file rings 1, 5 are butted.