Disclosed herein is an apparatus for producing a slide fastener having a separable end stop through the steps of attaching a pin, box pin, a slider and a box to a pair of stringers while the stringers are being fed in a parallel state by grippers, in which the stringers have a space portion devoid of fastener elements and upper stoppers affixed adjacent to the space portion. A slider attaching unit of this apparatus has a transfer holder for carrying the slider into the path of travel of the stringers from a slider supply device and a retaining device for retaining the slider between itself and the holder. The retaining device includes a stopper block and an engaging block which are driven so as to assume positions where both blocks cooperate with the transfer holder to retain the slider when the stringers are passed through the slider, after which the stopper block is driven so as to separate from the slider, whereby the slider is freed from between the transfer holder and engaging block automatically when the upper stoppers of the stringers engage the slider.