To maintain screw joint strength as well as to improve the workability of building construction and the like by making quick tightening possible.

This fastening member consists of a bolt 1 provided with a male screw thread 2 on its outside circumference and a nut 5 provided with a female screw thread 6 fitted to make a screw joint with the male screw thread 2 on the inside circumference. In this case, the male screw thread 2 of the bolt 1 is provided so that two screw threads 3, 4 are in a spiral shape parallel to each other from their respective starting ends 3a, 4a and the female screw thread 6 of the nut 5 is provided so that two screw threads 7, 8 are in a spiral shape parallel to each other from their starting ends corresponding to the male screw thread 2.