Torque wrench

The invention seek to enable to share main components other than a tightening unit even in use for different effective lengths corresponding to ranges of tightening torques. There are provided: a tightening unit such as a ratchet; a housing having a two-divided structure including a front side cover part and a back side grip part ; a strain body provided inside the housing and replaceably coupling the tightening unit thereto; a distortion sensor , provided to the strain body , for detecting the distorted amount of the strain body due to the tightening force of the tightening unit ; a microprocessor chip having functions including computing the tightening torque of the tightening unit based on torque reference values prepared in advance and detection results of the distortion sensor ; and an output unit for outputting such as the tightening torque.