Hexagonal wrench used for treating chamfering screw

The invention relates to a hex wrench dealing inverted screw, particularly a hex wrench with simple structure and high clamping stability, with one sleeve barrel end inserted into a matching shaft whose edge side forming into a semi circular cross section containing arc slot with a pair of clamps shoring against an elastic part at one side that is tilt up, protruding the edge of the matching shaft. When the matching shaft embedded into the inverted screw hex hole, it can use the protruded clamp stopping the falling of the corresponding angle of the hex hole to prevent the relative slippery to improve the clamping result in order to assist the effective drawing back of the inverted screw.