Abstract: The button fastener comprises a fastener body and a cover member which is attached to the fastener body. The fastener body includes a disk-like base and a hollow, cylindrical post extending upward from a center area of the base concentrically. The post has a top opening at its upper end and a bottom opening in a center area of the base. The cover member covers the lower surface of the base including the bottom opening. The base includes a base bottom adjacent to the post and a base flange rising upward relative to the base bottom radially outward from the base bottom. The cover member includes a curved outer periphery curving from the lower surface side of the base and then rising upward beyond the base flange of the base.