Molten resin is continuously extruded from an injection die or an extrusion die toward the circumferential surface of a die wheel having in its circumferential surface a multiplicity of hook-element-forming cavities and, at the same time, one or more yarns are introduced between the molten resin and the circumferential surface of the die wheel into an inter-element portion of a substrate sheet between a desired adjacent rows of hook elements in parallel to the hook element rows. The yarns are embedded in and integrally molded with the inter-element portion of the substrate sheet and at the same time, hook elements are molded on the circumferential surface of the die wheel as the hook-element-forming cavities are filled with part of the molten resin.