To hold the correcting stem and branch of a Bonsai (potted dwarf tree) to a right position in tensioned state, easily perform various tree form correcting works without necessitating skilled labor, prevent the damage of the root of the stem and improve the workability of the tree form correction work.

A pulling screw rod 2 is inserted into a tubular main body 1 in a longitudinally movable state while inhibiting the rotation. A pull-in port 4 is formed at the tip end of the tubular body 1, a hook 5 for hooking the middle part of a correction wire bound to the stem or branch of a Bonsai is protruded at the tip end of the pulling screw rod 2, a rotatable screw nut 6 screwable to the base of the pulling screw rod is rotatably placed on the tubular body in an unmovable state and a twisting rod 10 to be inserted into the loop of the wire W pulled in through the pull-in port is placed in freely insertable and removable manner.