A button fastener made of metal for fastening a button such as a male snap button or a decorative button to a cloth, includes a plate-like base and a cylindrical post projecting from a center area of the base. The upper end face of the post is open as a top opening, and the lower end face of the post is open in the center area of the base as a bottom opening. To the button fastener, a closing member which closes the inside of the post at a proximal side thereof is provided. The closing member is a closing part which has been cut out, by a punch, of an unfinished post of a semifinished product which is fabricated to the button fastener and then displaced by the punch through the inside of the unfinished post toward the lower end.