In this method for fastening a composite material component, the first smoothness is measured of a first fastening component disposed in a first countersink-provided hole formed in a first article to be fastened as a plurality of stacked composite material components. The depth of a second countersink is determined on the basis of the first smoothness. A second countersink-provided hole is formed at the second countersink depth in a second article to be fastened as a plurality of stacked composite material components. The second article to be fastened is fastened using a second fastening component disposed in the second countersink-provided hole.
