PURPOSE: To easily lock or release an adjustment sleeve by providing a transmission connecting member between an actuating ring and a locking ring.

CONSTITUTION: A chuck jaw 2 is moved by an adjustment sleeve 5 rotatable but not axially displaceable on the chuck body 6 for freeing and locking this drill chuck. The locking ring 13 for locking the adjustment sleeve 5 is provided with teeth 14, and these are locked with the opposite teeth 15 of the adjustment sleeve 5. Further, transmission connecting members 21, 22 are provided between an actuating ring 16 rotatable but not axially displaceable and the locking ring 13, and when the actuating ring 16 is turned, the locking ring 13 is moved by the transmission connecting members 21, 22 between the axial positions where the adjustment sleeve 5 is locked or released.