Slide fastener

In a slide fastener (1) according to the invention, each fastener element (10, 10', 30, 40) includes an upper half element portion (11, 31, 41) disposed at a first surface side of a fastener tape (2) and a lower half element portion (21) disposed at a second surface side of the fastener tape (2). The upper half element portion (11, 31, 41) includes a first tape-sandwiching portion (12, 32, 42), a first head portion (13, 13', 33, 43) of a tapered form, and a thin walled portion (16,36,46) which has a downward inclined surface (17,37a,37b,47) that is inclined downward toward the forefront of the first head portion (13,13',33,43) from the thin walled start portion set on the upper half element portion (11,31,41) to the first head portion side. Thereby, the fastener element (10, 10', 30, 40) can be formed lightweight and can make coupling breaking difficult to occur.