Abstract: An automatic lock slider for slide fasteners comprises a slider body having an upper and a lower wing connected by a neck portion, the upper wing having a recess for receiving a leaf spring and a through opening parallel with the leaf spring. A pull member is pivotally supported on the slider body and has at one of its ends a first cam held in abutting relation to the leaf spring and a second cam parallel to the first cam. A locking member is actuated by the second cam and has a locking prong movable through the through opening into the path of fastener elements and disposed in close proximity to the neck portion when the slider is in locked position. A support stud extends upwardly from the recess adjacent to the through opening and has a stop adapted to limit pivotal movement of the locking member, the stud serving as a pivot about which the locking member is rotatable.