The invention provides a slidable fastener assembling device which can install a metal stopper on a tooth chain provided with a first sliding part and a second sliding part. The slidable fastener assembling device comprises a first clamping device (20) clamping and transferring the continuous tooth chain C1; a cutting device (30) for cutting the continuous tooth chain C1 transferred by the first clamping device (20) into a tooth chain C2 of a specified length; a second clamping device (40) used for receiving and transferring the tooth chain C2 from the first clamping device (20); a first sliding part mounting device (50A) and a second sliding part mounting device (50B) used for mounting the first sliding part S1 and the second sliding part S2 on the tooth chain C2 transferred by the second clamping device (40); and a stopper mounting device (60) used for mounting a metal or resin stopper P2 on the tooth chain C2 transferred by the second clamping device (40).