The present invention provides a wrench which includes a movable jaw, a fixed jaw and a slidable member formed at the bottom portion of the movable jaw and slidably mounted to the main body. In the present invention, a toggle member can be driven to rotate through rotating a handle of the wrench, and the toggle member can smoothly move to and fro between a driving space and an evading space of the slidable member. Whereby, the present invention is simple in structure, has characteristics of smoothly engagedly-cooperative movements between parts of the wrench, so that it can make full use of the force applied by the user and has excellent effects of use.