To provide a book mark which becomes contracted between the pages of a note book when the note book is closed and stands upright away from the pages of the note book so that the book mark is not in the way for a reader to read the book when the note book is opened.

A vertical slit 5 is formed in the center of one piece of sheet and a pair of right/left book mark bodies 1 and 2 are provided on both sides on the slit 5. And further, a pair of right/left folding pieces 3 and 4 are provided at the upper part of the bodies 1 and 2 with a chevron-shaped folding line 6 in the same direction as the vertical slit 5, formed in between. The paired right/left book mark bodies 1 and 2 have holes 8 for a binder to pass through along the slit 5. In addition, two almost parallel and crosswise trough-shaped folding line 7 is provided between the left book mark body 1 and the left folding piece 3 and the right book mark body 2 and the right folding piece 4, respectively.