An improved chuck for a hand or powered drive tool includes a chuck head which has an axial inner hole and multiple through passages mounted with certain angle, the passages are crossed with the axial inner hole, each passage has a non-circular closing section on vertical shaft relative to the passage; multiple chuck jaws glidingly mounted in the passages, each chuck has tool joint part, screw thread machined on the reverse outer surface, and polygonal sections on the vertical shaft relative to the chuck jaws; and a mechanism for manipulating the chuck so that the chuck can clamp or release tool therewith. |