A tightening machine of the present invention includes: a mobile receiving portion 20 that receives a positioning signal (GNSS signal) from positioning means (GNSS satellite Sa); a geomagnetic sensor 30 that detects a direction of a socket portion 41 with the mobile receiving portion 20 as a starting point; and a control portion that receives the positioning signal received by the mobile receiving portion 20 and a positioning signal received by a fixed receiving portion 22 at a fixed position away from a torque wrench 110 serving as the tightening machine, corrects a three-dimensional position of the mobile receiving portion 20 based on the positioning signals, and calculates a three-dimensional socket position of the socket portion 41 of the torque wrench 110 serving as the tightening machine based on a result of the correction and the direction of the socket portion 41 detected by the geomagnetic sensor 30.