To provide a bookmark which is provided with plural arm parts so that a bookmark body can be automatically reheld when pages are turned over in whichever direction, forward or backward, and which can reduce its projection to the outside of a book.

There is provided an automatic bookmark comprising a base part 4 fixed to the front cover and back cover of a book, a plurality of shoulder parts 3 provided at an upper end of the base part 4 on the front cover side and an upper end on the back cover side, flexible arm parts 2 each extending from each shoulder part 3 in the direction opposite to the side of an opening/closing axis 10 of the book, and a single bookmark body part 1 supported at a free end of each arm part 2. When the book is opened, the arm parts 2 move the bookmark body part 1 toward the front or back surface of the book to move and hold the bookmark body part 1 between spread pages, and when the book is closed, a front end of the bookmark body part 1 is inserted between the pages which are spread last.