A vehicle seat includes: a first member; a second member; an insertion fastening structure configured to apply an axial tension to an opposed surface portion of the first member and an opposed surface portions of the second member so as to be pressed against each other; and an adjustment member. The opposed surface portion of the second member includes different surface shape portions facing respective surfaces toward directions different from an application direction of the axial tension, and the adjustment member plastically deforms the opposed surface portion of the second member such that the opposed surface portion of the second member, including the different surface shape portions, is pressed and sandwiched between the adjustment member and the opposed surface portion of the first member by the application of the axial tension.