A wrench includes a handle, a yoke, a shaft, a head, a mandrel, a first transmitting unit and a second transmitting unit. The shaft includes a first section securely connected to the handle and a second section rotationally inserted in the yoke. The head is pivotally connected to the yoke. The mandrel is inserted through the head. The first transmitting unit can be used to transmit a small torque to the mandrel from the handle spun relative to the yoke. The second transmitting unit can be used together with the first transmitting unit to transmit a large torque to the mandrel from the handle pivoted together with the yoke.