Provided is a slide fastener that has a flexible fastener tape, exhibits liquid-tightness, and can prevent a gap from being formed in a coupling portion, and a method of producing the slide fastener. An overlay material is formed on a front surface of a fastener tape so that the overlay material formed on a surface of a core member extends beyond a centerline in a front-rear thickness direction of a tape member. When a pair of fastener element rows engages with each other, a tip of an intermeshing head of a fastener element presses the overlay material formed on the opposite core members.