To prevent a position of a screw in a once determined screw hole from being dislocated by impact by hindering a head part of the screw from moving from a fastening position by a position determining part in a condition where a binding device is fixed to a board by the screw.

In a pressing-down plate 1, screw inserting holes 10 are arranged in four places, and a central position of the respective screw inserting holes 10 is arranged so as to become a central position of a square. A long hole- shaped inserting hole 5 being a long hole-shaped inserting part, head receiving areas 6 being position determining parts arranged in three places so that a screw 8 can be fixed along this long hole-shaped inserting hole 5 and a washer receiving area 7 on its periphery are arranged in these screw inserting holes 10. The screw 8 is inserted into the long hole-shaped inserting hole 5 in a condition of being inserted into a washer 9, and is screw-fitted to a board, and the head receiving areas 6 arranged around the long hole-shaped inserting hole 5 fix a head part of the screw 8 from a side surface when the screw is screw- fitted to the board, and prevent a movement of the screw 8.