A chuck for a boring tool, which allows one-handed operation when changing the tool, is known from German Published Patent Application No. 100 26 021. For this purpose, the chuck has a chuck body having an insertion opening, into which a tool shank may be axially inserted. In the inserted state, the tool shank may be axially locked by locking bodies, the locking bodies engaging in axially running grooves in the tool shank, so that the tool shank has a specific movement play in the axial direction in the locked state. For this purpose, radial yielding movement of the locking bodies is prevented by an axially displaceable locking sleeve when the locking sleeve is in a locked position. In contrast, when the locking sleeve is pushed into an unlocked position by the operator, the locking bodies may yield radially outward and the boring tool may be removed from the chuck or inserted into the chuck. The locking sleeve is pre-tensioned in the direction of the locked position by a spring in this case, in order to prevent unintentional unlocking of the boring tool. To allow one-handed operation, however, the locking sleeve may be axially arrested in the unlocked position, the arresting being performed by a leaf spring, for example, which engages in the locking sleeve from the inside.