An adjustable wrench for driving a nut utilizes curved drive faces. The wrench is made up of three members. A first member has a jaw section, a mid section and a handle section. A second member has a jaw section and an attachment section for attaching to the first member in the mid section and adjusting the spacing of the jaws. A third member fits within the first member and attaches the first member to the second member in an adjustable manner in the mid section of the first member. The jaws of the first and second members have convex curved surfaces having forward and rearward drive faces. These convex curved surfaces form gripping members which drive the nut or bolt on the planes and not on the corners.