A hand-held power tool with a quick-clamping device for a working element includes a working mandrel for driving the working element, a fastening member for fastening the working element onto the end of the working mandrel, and a locking assembly. The fastening member includes a clamping shaft insertable into the working mandrel and a moving assembly for making the fastening member moveable between a releasing position and a clamping position. The locking assembly includes a floatable clamping component and the clamping component and the clamping shaft are provided with corresponding toothed portions such that engagement and disengagement therebetween is selectively achieved by the relative rotation of the toothed portions.