A wrench includes a body having a mounting hole. Three first driving portions and three second driving portions are formed in the inner periphery of the mounting hole, and the first and second driving portions are located alternatively to each other. Three first recesses and three second recesses are formed in the inner periphery of the mounting hole, and the first and second recesses are located alternatively to each other. Each first recess is connected between the first and second driving portions. The mounting hole is used to mount to an object which is rotated when the wrench is rotated.