A yarn splicer according to the present invention ensures that yarn splicing can be carried out with elastic yarns being reliably caught and held, and prevents the absence of core yarns in a spliced portion. The splicer comprises: a pair of cutters 11 and 12 for cutting stretchable elastic yarns; a yarn splicing member 2 for applying compressed air to yarn ends of two elastic yarns Y1 and Y2 respectively cut by the cutters 11 and 12; and splicing holes 16 and 17 provided in the yarn splicing member 2 for guiding the yarn ends Y1 and Y2 so as to be placed together, and the splicer further includes a means for forming a catch-and-hold slit 21 for catching and holding the yarns Y1 and Y2 in the splicing holes 16 and 17, respectively, by utilizing length contraction and thickness expansion of each of the elastic yarn Y1 and Y2, which occurs when the elastic yarns are cut by the cutters 11 and 12.