Slide fastener

A slide fastener, comprising:

• a pair of left and right fastener tapes;
• and
• a plurality of synthetic resin fastener elements lined along opposing tape side edge portions of the fastener tapes,
• each fastener element including an upper half element portion disposed at a first surface side of the fastener tape and a lower half element portion disposed at a second surface side of the fastener tape,
• the upper half element portion including a first tape-sandwiching portion having a predetermined dimension in a tape length direction, and a first head portion of a tapered form that extends from the first tape-sandwiching portion toward an outside of the tape up to a forefront position of the lower half element portion and has a dimension in the tape length direction that gradually decreases toward the forefront,
• the lower half element portion including a second tape-sandwiching portion that sandwiches the fastener tape together with the first tape-sandwiching portion, a neck that extends from the second tape-sandwiching portion toward the outside of the tape and has a shape constricted in a front and rear of the tape length direction, and a second head portion that extends from a forefront portion of the neck and bulges in a front and rear of the tape length direction,
• wherein the first head portion includes a first narrow width portion arranged on the first tape-sandwiching portion side and a second narrow width portion arranged on an element forefront side via an inflection portion from the first narrow width portion, and
• a dimension in a tape length direction between a front side surface and a rear side surface of the first tape-sandwiching portion and the first head portion gradually decreases towards an upper surface of the upper half element portion.