| 摘要 |
PROBLEM TO BE SOLVED: To provide a looseness preventing nut capable of easily and surely performing fastening a nut with precise tightening torque. SOLUTION: In the looseness preventing nut comprised of an upper nut 3 and a lower nut 2, a contact portion 3b that gets in contact with a lower end portion of a tightening tool such as a wrench and the like during tightening work of the upper nut is arranged in the upper nut 3. Further, the contact portion 3b, for example, is protruded from a part of an outer periphery of the upper nut, and a rotating amount of the upper nut 3 is set to be capable of visually confirming.
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