To rotate a binding in a horizontal direction and to adjust an angle to the longitudinal direction of a board.

This structure is composed of an adjustment body 11 in an almost circular plate shape and a fixing member 12 fixed to the board 13 for locking the adjustment body while passing through a binding main body 10 in slidable contact with the surface from an upper part and holding the main body, and engagement parts 14 provided in a prescribed pitch in the peripheral direction of the slidable contact surface of the adjustment body are provided. Plural through-holes 15 and locking holes 19 are pierced on the inner peripheral side of the engagement part 14 and locking projections to be inserted to the locking holes 19 and locked are provided on the lower part of the fixing member 12. Further, an annular sliding surface capable of sliding on the adjustment body is provided on the lower part of the main body, a positioning member 25 to appear downwards from the main body and to be engaged with the engagement part is provided, the main body slides the adjustment body in the peripheral direction and the position is fixed by the engagement of the positioning member.