Fastener Element, Fastener Stringer and Slide Fastener

A fastener element for a slide fastener made of synthetic resin which is injection molded at tape side edge parts of fastener tapes, having a central land portion fixed to the fastener tape and first and second bulging portions bulging from the central land portion to a tape front surface side and a tape rear surface side in an element thickness direction, wherein the central land portion has a body portion fixed to the fastener tape with a predetermined dimension in an element width direction, a neck portion extending from the body portion to a tape outward side in an element length direction and a coupling head portion further extending from the neck portion in the element length direction, wherein;

• the first and second bulging portions have a bulging end surface facing upward or downward in the element thickness direction and a pair of top and bottom side wall surfaces formed from top and bottom side edges of the bulging end surface to the central land portion respectively,
• the bulging end surface has a quadrilateral-shaped base end surface which is composed of four sides of a tip end edge on the coupling head portion side, a tail end edge of the body portion side and the pair of side edges connecting both ends of the tip end edge and both ends of the tail end edge and is long in the element length direction and also has a protrusion end surface protruding from only a part of one of the side edge out of the pair of top and bottom side edges of the base end surface in the element width direction, and
• the protrusion end surface is formed on the coupling head portion and has a shape which tapers gradually toward a protrusion direction from the base end surface.