In a locking wrench designed to grip an object between a stationary and a movable jaw firmly under the action of a toggle link associated at one end with the movable jaw and at the other end with a threaded bolt, the movable jaw is divided into two separate parts, that is, a body member pivotally secured to the stationary jaw and a grip member supported on the body member for sliding movement relative thereto so that the distance between the grip faces of the grip member and the stationary jaw may be adjusted as desired. With this structure, an optimum force of grip is readily obtainable at all times for thickness of the object to be gripped without the need of adjusting the threaded bolt therefor.