A torque wrench with constant torque comprises a wrench body having a tube and a cavity, an adapter, a pillar, a clutching member, a handle, and a resilient member. Therein, the adapter is rotatably disposed in the cavity, with plural adapting parts disposed on the outer periphery thereof. The pillar is disposed between the tube and the cavity for resisting against the adapting part. The clutching member is disposed in the tube, with a first end resisting against the peripheral surface of the pillar, a second end and a peripheral edge rollingly contacting the inner edge of the tube. The handle is connected to one end of the tube. The resilient member is disposed inside the tube for resisting against the second end of the clutching member. Thus, the torque is transmitted directly and prevented from diminishing, maintain a precise torque value.