PURPOSE: To insert a plurality of inserting rods provided at a retaining plate into a plurality of cylindrical binder rods provided at a binder body even if the inserting rods are not accurately aligned with the binder rods when the inserting rods are inserted into the binder rods and to easily insert the inserting rods into the binder rods.

CONSTITUTION: The binder comprises a binder body 1 having a plurality of cylindrical binder rods 13, and a retaining plate 2 having inserting rods 22 to be inserted into the rods 13, a rising wall 12 having a locking part 15 and provided at the body 1, and a locking unit 3 engaged with the part 15 to maintain a closed position of the plate 2 at the plate 2. The plate 2 has a guide piece 4 for guiding the rods 22 to the rods 13 in contact with the wall 12 when the rods 22 are inserted into the rods 13, and a position control unit 5 for setting the plate 2 to the body 1 by engaging it with the wall 12.