A liquid-tight slide fastener, wherein a pair of right and left coil-like coupling element rows, through which a core thread is respectively passed, is attached by sewing along opposing side edges of a pair of right and left fastener tapes, the fastener tapes having a liquid-tight layer on one surface thereof, and the core thread is coated with a water repellent agent or oil repellent agent. Consequently, even if water or oil invades into a space portion in the coupling element rows through a joint portion in the liquid-tight slide fastener, the core thread repels the water or oil, thereby blocking a further invasion of water or oil, and exerting excellent water repellency or oil repellency without provision of a water stop flap.