A folding clasp for bracelets comprising: - a sequence of at least two longitudinal segments (51, 52; 151, 152, 60, 260) articulated with respect to one another so as to form the folding blades of the clasp; - a first (2; 102) and a second (3; 103) bracelet connecting member intended to be connected to a first and a second free end of the bracelet respectively, with the first connecting member being fixed to a first longitudinal segment and the second connecting member being fixed to another one of the at least two longitudinal segments; - clasp locking means (4; 104) for closing and opening the clasp; and, - a device (5; 105; 205) for adjusting the length of the bracelet comprising a movable part (10; 110; 210) connected to one of the two connecting members, and a support (45; 145; 245) fixedly attached to one of the longitudinal segments, with said adjusting device comprising a locking device (20-23; 120-125a; 220-225) capable of assuming two stable positions, i.e. one unlocking position in which the movable part (10; 110; 210) can be moved in the lengthwise direction of the bracelet so as to enable adjustment, or a locking position, in which any movement of the movable part relative to the support is locked, characterized in that said locking device comprises a locking part (20, 120; 220a, 220b) and a locking slide (21, 121, 221) comprising a grasping and handling member (21a; 121a; 221a) which can be shifted and/or slid by a wearer in order to move from the locking position to the unlocking position, in that said grasping and handling member (21a; 121a; 221a) is a separate and/or different part from said locking part (20, 120; 220a, 220b), and in that said locking part (20, 120; 220a, 220b) directly cooperates with the movable part (10; 110; 210) and is accommodated in the adjusting device (5; 105; 205) so that, in the locking position, said locking slide (21, 121, 221) prevents any movement of said locking part and in that, in the unlocking position, said locking part can move, in order to enable a movement of the movable part. - a sequence of at least two longitudinal segments (51, 52; 151, 152, 60, 260) articulated with respect to one another so as to form the folding blades of the clasp; - a first (2; 102) and a second (3; 103) bracelet connecting member intended to be connected to a first and a second free end of the bracelet respectively, with the first connecting member being fixed to a first longitudinal segment and the second connecting member being fixed to another one of the at least two longitudinal segments; - clasp locking means (4; 104) for closing and opening the clasp; and, - a device (5; 105; 205) for adjusting the length of the bracelet comprising a movable part (10; 110; 210) connected to one of the two connecting members, and a support (45; 145; 245) fixedly attached to one of the longitudinal segments, with said adjusting device comprising a locking device (20-23; 120-125a; 220-225) capable of assuming two stable positions, i.e. one unlocking position in which the movable part (10; 110; 210) can be moved in the lengthwise direction of the bracelet so as to enable adjustment, or a locking position, in which any movement of the movable part relative to the support is locked, characterized in that said locking device comprises a locking part (20, 120; 220a, 220b) and a locking slide (21, 121, 221) comprising a grasping and handling member (21a; 121a; 221a) which can be shifted and/or slid by a wearer in order to move from the locking position to the unlocking position, in that said grasping and handling member (21a; 121a; 221a) is a separate and/or different part from said locking part (20, 120; 220a, 220b), and in that said locking part (20, 120; 220a, 220b) directly cooperates with the movable part (10; 110; 210) and is accommodated in the adjusting device (5; 105; 205) so that, in the locking position, said locking slide (21, 121, 221) prevents any movement of said locking part and in that, in the unlocking position, said locking part can move, in order to enable a movement of the movable part.