Fastening structure, fastening method and fastening member

A fastening structure in which a first member and a second member are mutually connected by a fastening member including a threaded portion, the fastening structure comprising:

• a tubular projecting portion provided on the first member;
• and
• at least one slit formed in the tubular projecting portion,
• wherein
• the tubular projecting portion raises from one surface of the first member toward the second member and inwardly defines a hollow portion,
• the second member is formed with a hole in which the tubular projecting portion is inserted,
• the slit extends from a leading end of the tubular projecting portion to a base end thereof and which continues to the first member,
• the tubular projecting portion having a constant wall thickness from the leading end to the base end,
• the threaded portion of the fastening member includes an outer diameter larger than a minimum inside diameter of the hollow portion of the tubular projecting portion and smaller than a hole diameter of the second member,
• the threaded portion is screwed into the hollow portion of the tubular projecting portion inserted into the hole of the second member, and
• the tubular projecting portion is formed with a radially expanded portion by expanding the tubular projecting portion radially and outwardly by screwing the threaded portion, the radially expanded portion being formed by a leading end of the tubular projecting portion projecting from the hole of the second member being deformed and the first member and the second member are mutually fastened in a state where an outer circumference surface of the radially expanded portion abuts on a peripheral wall of the hole of the second member to cover an opening edge portion of the hole of the second member, as the threaded portion is screwed into the hollow portion of the tubular projecting portion,
• wherein the hollow portion defined by the tubular projecting portion is a hollow portion whose both ends are open, penetrating the first member in its through-thickness direction.