To provide an automatic bookmark in which a position of a bookmark body can be always and stably held at a required position.
The automatic bookmark 13 is constituted of a rectangular sheet made of a sheet of a synthetic resin. The second base sheet 16 is folded back at the first parts 25a and 25b with respect to the first base sheet 15. The bookmark body 18 is so constituted that it extends from the first base sheet 15 at the second part 27 positioned between the first parts 25a and 25b. The bookmark body 18 is folded downward ahead at a part of a connecting part 19 so that a triangle piece part 20 at the tip is along the face of the second base sheet 16 along a folding line 23. When it is used, it is used by setting the automatic bookmark 13 so that a page sheet behind a book is pinched with the first base sheet 15 and the second base sheet 16. As the automatic bookmark 13 is supported thereby by the page sheet, there exists no possibility of shifting when it is used.