A pipe wrench includes a fixed jaw with alternatively located first recesses and first driving faces defined in the inner side thereof. A pivotal member is pivotably connected to the fixed jaw and a resilient member is biased between the fixed jaw and the pivotal member. The pivotal member has alternatively located third recesses and second driving faces. A hexagonal space is defined between the first and second driving faces. The end portion of the pivotal member is inserted into a second recess defined in the inner side of the fixed jaw. The object is clamped in the hexagonal space, and the pivotal member can be pivoted away from the fixed jaw. The pipe wrench is able to quickly clamp and dismounted from the object.