Abstract: A slider aligning device is disclosed for use in a separable slide fastener of the class comprising a pair of stringers having longitudinal rows of interfitting fastener elements on their opposed edges respectively, and a pair of sliders arranged reversely to each other on the rows of fastener elements for longitudinal movement therealong to engage and disengage the same. The aligning device includes a pair of recesses formed inconspicuously at the contracted end of one of the sliders, and a pair of tongues formed correspondingly at the opposed contracted end of the other slider. The tongues are so shaped and sized as to fit neatly in the respective recesses when the contracted ends of the two sliders are brought into contact with each other, so that the sliders can be held in correct alignment during insertion or removal of a pin member at one end of one of the stringers into or out of the guide channels of the respective sliders.