An apparatus for manufacturing a continuous slide fastener stringer (11) including a plurality of longitudinally spaced rows of injection-molded coupling elements (13) secured to a stringer tape (12) along a longitudinal edge thereof with a plurality of element-free portions between the successive rows of the injection-molded coupling elements, includes a fixed feeler (70) disposed on the one of a pair of relatively movable mold members (14, 15) adjacent to a leading mold cavity therein for detecting a trailing end (73) of the injection-molded coupling elements, and a movable feeler t74) disposed on the one mold member (15) downstream of the fixed feeler (70) at a distance (W) substantially equal to the length of the element-free portions of the stringer. The movable feeler (74) is driven by a driving mechanism to selectively project or retract from a mold surface (26) of the one mold member (15) in interlocking relation with a feed mechanism (63, 66) which intermittently feeds the stringer tape by a predetermined distance.