To obtain an aluminum-based member made highly decorative by a simple method.

On the surface of the aluminum-based material, a first mask forming step (step S102) is performed, and a hairline processing is given to the aluminum-based material through the opening of a first mask (step S103). The first mask is eliminated (step S104), and then, a second mask is formed as a pattern different from that of the first mask in a second mask forming step (step S105). Then, a scratch line is formed in a direction orthogonal to a hairline processing direction through the opening of the second mask (step S103).