A wrench includes a transmitting device and a shell. The transmitting device comprises a rotor, a first working member, a second working member, a first linking member and a second linking member. The first linking member is disposed between the first working member and the rotor. The shell has a containing room for the linking device to be disposed therein. The shell comprises a middle section. The first end of the middle section extends upwardly to connect with the first section. The second end of the middle section extends downwardly to connect with the second section. Thus, the wrench has two stair portions of different horizontal level. And Users can hold the wrench more stably. Because the wrench uses the rotor and two linking members to drive the first working member and the second working member rotating, a total size of the wrench can be kept as smaller as possible.