PURPOSE: To prevent a thread of a threaded handle from being slackened by vibration by constituting a joining system by means of both threaded handle, which is used to fix a joining body to a body to which the joining body is joined (hereafter referred to as 'joined body') and a lever, which is installed in such a manner that it is rotated by a spring so as to be fitted in the threaded handle.

CONSTITUTION: When a joining body 2 comes to a fixing position, a lever 4 is pushed in the arrow-marked direction, so that the lever 4 is disconnected from a groove of a threaded handle 3. Next, the threaded handle 3 is rotated until the joining body 2 contacts a 'joined body' 1. At this time, the released lever 4 is fitted in the nearest one of a plurality of grooves grooved on the threaded handle 3. Thus, even if vibration or large force acts on the joining body 2, the lever 4 will not be disconnected from the groove of the threaded handle 3, owing to the force of a spring 5. At the same time, the threaded handle 3 will not rotate in the direction in which the handle is slackened. Therefore, the joining body 2 can firmly be fixed to the 'joined body' 1.