Abstract: A quick-operating bench vise comprises a movable jaw with a slide and provided with a lead screw, a fixed jaw formed with a box shaped structure through which the slide of the movable jaw is accommodated, a clutching device including a half nut for engaging with and disengaging from the lead screw and a sector gear device operating in association with the lead screw. By turning the lead screw counterclockwise with the handle provided on the end thereof, the half nut is disengaged from the lead screw to permit quick moving of the movable jaw by pulling or puhing and by turning the lead screw clockwise, the half nut is engaged with the lead screw for clamping or releasing the work piece.