Through-holes are formed at a constant pitch along a side-edge portion of a fastener tape where a tape base fabric is covered by a waterproof layer, the through-holes piercing the fastener tape. Plasma treatment or corona treatment is applied to the side-edge portion of the fastener tape so as to form an activation region on a surface of the waterproof layer on one or both sides of the fastener tape. Injection molding of fastener elements is performed to attach the fastener elements to the side-edge portion of the fastener tape. Melted resin adheres to the activation region and fills the through-hole before solidifying into the fastener element.