The present invention provides a fastening structure and a fastening method for fastening first and second components, ensuring a high degree of freedom in terms of bonding positions and objects, and reducing the number of holes in the components. Specifically, the present invention provides a fastening structure for fastening the first and second components, wherein said fastening structure comprises a pin that has non-helical grooves running in a circumferential direction and aligned along a longitudinal direction, and a collar that is fitted around said pin, and said pin is united with said first component by bonding one end of said pin in the longitudinal direction to said first component without forming a hole in said first component, and said second component has a hole for inserting said pin so that said collar is fitted around and swaged to said pin protruding through the hole.