Abstract: A fastener comprises a base formed of a flange and a plurality of leg pieces and a screw-receiving member adapted to be embraced between the leg pieces, whereby it is secured onto a given panel by a procedure which involves inserting the leg pieces into a fitting hole bored in advance in the panel, then inserting a fastening screw through a through hole formed in the flange into a screw hole formed within the screw-receiving member, imparting a helical motion of the fastening screw thereby drawing the screw-receiving member toward the flange, consequently causing the leg pieces to be spread outwardly within the fitting hole of the panel and brought into tight engagement with the fitting hole and, at the same time, enabling the fastening screw to be secured onto the panel through the medium of the base.