In the first part of this study, the tightening experiments are performed with emphasis on an evaluation of tightening characteristics using threaded fastener tightening test machine. As a result of the above experiment, the coefficient of variation in the distribution of axial force by the torque gradient control method which tightens bolts up to the limit of elasticity is found to be about one-third of that obtained by the torque control method which tightens bolts in the elastic region. Secondly, the fatigue tests are performed with the bolted joint of two cylinders tightened by the elastic limit tightening or by the elastic region tightening. It is confirmed that the bolted joint tightened to the limit of elasticity has the better safety against fatigue than that tightened in the elastic region by the torque control method.