To provide an automatically inserted bookmarker which enables a bookmarker to automatically move when a page is turned in reading and can indicate the section without moving the bookmarker by hand even when reading is interrupted.

The automatically inserted bookmarker is composed of a base sheet having a square hole, through which a bookmarker part of a bookmarker body mounted to the rear side of the base sheet is put out to the front side, at the upper part of the base sheet, and the bookmarker body, in which the bookmarker body and the bookmarker part are formed of one sheet, the bookmarker part is folded back at a fold, and a notch for imparting elastic force of the bookmarker part is provided at the root of the bookmarker part. The automatically inserted bookmarker is adhered to the rear side of the base sheet. The bookmarker part is passed to the front side of the base sheet through the square hole. The automatically inserted bookmarker is fixed to the upper part of a fly leaf on the rear side of a book so as to be sandwiched by the base sheet and the bookmarker body when used. The bookmarker part is moved to the opened page.