PURPOSE: To hold an arbitrary page of a book and the like in an open state by providing a pair of rotary shafts which has parallel axes at the seam of the book and independently rotate at a plate for mounting the seam of the book, and providing a pair of page retaining members at each shaft.

CONSTITUTION: In the case of using, a seam 12 is mounted on the plate 15 of a page retaining implement 10 for a book 11 in the state that the book 11 is opened. Then, the positions of page retaining members 23, 24 are so moved that the relative position to the plate 15 is varied while rotating a pair of rotary shafts 17, 18. Then, the pages 13, 14 of the book 11 are retained by the ends 25, 26 of the members 23, 24. The shafts 17, 18 are independently rotated against the frictional force of a frictional mechanism 20. Thus, the ends 25, 26 of the members 23, 24 can similarly retain both the pages 13, 14 of the book 11 in response to the thicknesses of the pages 13, 14.