In this study an investigation was made for the bolting methods and bolting torque for high strength bolts generally used in Korea as well as in abroad together with an inspection on the selection of high strength bolts and bolting torque for automotive manufacturing lines, those were implemented during the course of analyzing the causes of de-crease in operating rate in the automotive manufacturing factories. As a result of this investigation, 100 % of bolting torque did not meet the criteria specified in KS Standard, causing malfunctioning of the mechanical facilities due to loosening of bolts during the operation, which in turn is turned out to be the major cause of lowering operating rate. The purpose of this study is to check the bolting status compared with KS B 0140: 1991, a standard for bolting torque of high strength bolts, and to analyze the effect of the bolting status onto the operating rate, ultimately to give suggestions on the importance and improving measures for bolting of high strength bolts