Wrench having rotation adjustment effect

A wrench, comprising a first handle, and a second handle combined with the first handle, wherein:

• the first handle has a first end provided with a first rotation seat;
• the second handle has a first end provided with a second rotation seat rotatably mounted on the first rotation seat of the first handle;
• the wrench further comprises a rotation shaft rotatably mounted between the first rotation seat of the first handle and the second rotation seat of the second handle;
• the first rotation seat of the first handle has a central portion formed with a first receiving hole, the second rotation seat of the second handle has a central portion formed with a second receiving hole aligning with the first receiving hole, the rotation shaft has a first end rotatably mounted in the first receiving hole of the first rotation seat of the first handle, and a second end rotatably mounted in the second receiving hole of the second rotation seat of the second handle;
• the first rotation seat of the first handle has a peripheral wall formed with a first positioning hole communicating with the first receiving hole, the first end of the rotation shaft is formed with a first annular groove aligning with the first positioning hole, and the wrench further comprises a first positioning pin mounted in the first positioning hole of the first rotation seat of the first handle and having a distal end slidably mounted in the first annular groove of the rotation shaft to prevent the first rotation seat of the first handle from detaching from the rotation shaft.