A waterproof slide fastener with waterproof property in which covering the whole front and rear faces of a woven or knitted fastener tape with an elastomer, and fastener elements made of a thermoplastic resin are injection molded on the lateral edge of the fastener tape. In particular, a waterproof slide fastener that can maintain the watertightness and airtightness even when the fastener tape is bent in the lengthwise direction because, on the assumption that the minimum width between the outer end edges of the neck part of the fastener element in the lengthwise direction of the fastener tape that is a slide direction in which the slider slides is N and the width between the outer end edges of the body part of the fastener element in the same lengthwise direction is B, the value of B/N is between 2.5 and 3.5.