To easily prevent the falling-off of a bolt from a bolt hole when a nut is screwed into the bolt.

In a member fastening method by a nut and a bolt for inserting a bolt 10A from the bolt hole 8A of one member 8 into the bolt hole 9A of the other member 9, screwing a nut 12 into the foot part of the bolt 10 protruded from the bolt hole 9A of the other member 9, and thereby fastening one member 8 to the other member 9, a ring 11 made of a flexible material is fitted in the foot part of the bolt 10 beforehand such that after the bolt 10 is inserted, the ring 11 is placed outside the bolt 9A of the other member 9.