To provide a structure of a fastening part that secures reliability and durability without increasing costs.

A structure of a fastening part of a resin molding component includes: a resin molding component through which a fixation hole penetrates; and an annular part that is formed of a member harder than the resin molding component, and is fitted into the fixation hole. A protrusion part is formed at the annular part or the fixation hole, which is formed so as to become higher than a gap formed by the fixation hole and the annular part.