Abstract: In a push rivet consisting of a grommet part and a pin part so that two panel members may be joined together first by passing the grommet part through an opening passed through these panel members, and forcing the pin part into a central bore of the grommet part to radially expand the free end of the grommet part, because the head of the pin part is provided with an outer profile which conforms to an outer profile of a part of the flange surrounding the pin head when the pin part is completely forced into the central bore, the fastener presents a smooth appearance which is pleasing to the eyes, and the pin part is prevented from being inadvertently pulled out of the grommet part even when an external object is struck against the pin head. However, a gap is defined between the pin head and the surrounding part of the grommet part so that the push rivet can be readily unfastened by fitting a pointed end of a tool into the gap, and pulling the pin part out of the central bore by using the tool as a lever.