A constant torque tool provided, including: a driver body, including a handle and a working rod connected with the handle, at least one of the handle and the working rod being integrally formed with a first blocking structure; a sleeve member, being rotatably disposed around the driver body and integrally formed with a second blocking structure, the second blocking structure being releasably stuck with the first blocking structure in a rotation direction of the sleeve member; wherein when there is a relative torque greater than a predetermined torque between the sleeve member and the driver body, at least one of the second blocking structure and the first blocking structure deforms and the second blocking structure is slidable over the first blocking structure in the rotation direction.